diff --git a/Libraries/SPTarkov.Server.Core/Controllers/CustomizationController.cs b/Libraries/SPTarkov.Server.Core/Controllers/CustomizationController.cs
index 71bf1447..85bcbfff 100644
--- a/Libraries/SPTarkov.Server.Core/Controllers/CustomizationController.cs
+++ b/Libraries/SPTarkov.Server.Core/Controllers/CustomizationController.cs
@@ -40,13 +40,11 @@ public class CustomizationController(
         var clothing = databaseService.GetCustomization();
         var suits = databaseService.GetTrader(traderId).Suits;
 
-        var matchingSuits = suits?.Where(s => clothing.ContainsKey(s.SuiteId)).ToList();
-        matchingSuits = matchingSuits
-            ?.Where(s =>
-                clothing[s.SuiteId]?.Properties?.Side?.Contains(pmcData?.Info?.Side ?? string.Empty)
-                ?? false
-            )
-            .ToList();
+        var matchingSuits = suits?.Where(s => clothing.ContainsKey(s.SuiteId));
+        matchingSuits = matchingSuits?.Where(s =>
+            clothing[s.SuiteId]?.Properties?.Side?.Contains(pmcData?.Info?.Side ?? string.Empty)
+            ?? false
+        );
 
         if (matchingSuits == null)
         {
@@ -58,7 +56,7 @@ public class CustomizationController(
             );
         }
 
-        return matchingSuits;
+        return matchingSuits.ToList();
     }
 
     /// <summary>
diff --git a/Libraries/SPTarkov.Server.Core/Extensions/FullProfileExtensions.cs b/Libraries/SPTarkov.Server.Core/Extensions/FullProfileExtensions.cs
index 4aec8c59..aa6569bc 100644
--- a/Libraries/SPTarkov.Server.Core/Extensions/FullProfileExtensions.cs
+++ b/Libraries/SPTarkov.Server.Core/Extensions/FullProfileExtensions.cs
@@ -12,7 +12,10 @@ namespace SPTarkov.Server.Core.Extensions
         /// </summary>
         /// <param name="fullProfile">Profile to add clothing to</param>
         /// <param name="clothingIds">Clothing Ids to add to profile</param>
-        public static void AddSuitsToProfile(this SptProfile fullProfile, List<MongoId> clothingIds)
+        public static void AddSuitsToProfile(
+            this SptProfile fullProfile,
+            IEnumerable<MongoId> clothingIds
+        )
         {
             fullProfile.CustomisationUnlocks ??= [];
 
diff --git a/Libraries/SPTarkov.Server.Core/Extensions/ItemExtensions.cs b/Libraries/SPTarkov.Server.Core/Extensions/ItemExtensions.cs
index 26743cb5..ec03e463 100644
--- a/Libraries/SPTarkov.Server.Core/Extensions/ItemExtensions.cs
+++ b/Libraries/SPTarkov.Server.Core/Extensions/ItemExtensions.cs
@@ -234,7 +234,7 @@ namespace SPTarkov.Server.Core.Extensions
         ///     Gets the identifier for a child using slotId, locationX and locationY.
         /// </summary>
         /// <param name="item">Item.</param>
-        /// <returns>SlotId OR slotid, locationX, locationY.</returns>
+        /// <returns>SlotId OR slotId, locationX, locationY.</returns>
         public static string GetChildId(this Item item)
         {
             if (item.Location is null)
@@ -365,7 +365,7 @@ namespace SPTarkov.Server.Core.Extensions
         /// </summary>
         /// <param name="items">Inventory items to look for secure container in</param>
         /// <returns>List of ids</returns>
-        public static List<MongoId> GetSecureContainerItems(this List<Item> items)
+        public static List<MongoId> GetSecureContainerItems(this IEnumerable<Item> items)
         {
             var secureContainer = items.First(x => x.SlotId == "SecuredContainer");
 
@@ -417,7 +417,7 @@ namespace SPTarkov.Server.Core.Extensions
         /// <param name="newId">Optional: new id to use</param>
         /// <returns>New root id</returns>
         public static MongoId RemapRootItemId(
-            this List<Item> itemWithChildren,
+            this IEnumerable<Item> itemWithChildren,
             MongoId? newId = null
         )
         {
@@ -450,7 +450,7 @@ namespace SPTarkov.Server.Core.Extensions
         /// </summary>
         /// <param name="inventoryItems">Items to hash</param>
         /// <returns>InventoryItemHash</returns>
-        public static InventoryItemHash GetInventoryItemHash(this List<Item> inventoryItems)
+        public static InventoryItemHash GetInventoryItemHash(this IEnumerable<Item> inventoryItems)
         {
             // Group by parentId + turn value into mongoId as we've filtered out non-mongoId values
             var byParentId = inventoryItems
diff --git a/Libraries/SPTarkov.Server.Core/Extensions/LootContainerSettingsExtensions.cs b/Libraries/SPTarkov.Server.Core/Extensions/LootContainerSettingsExtensions.cs
index a6037e33..4b5c9693 100644
--- a/Libraries/SPTarkov.Server.Core/Extensions/LootContainerSettingsExtensions.cs
+++ b/Libraries/SPTarkov.Server.Core/Extensions/LootContainerSettingsExtensions.cs
@@ -44,7 +44,7 @@ namespace SPTarkov.Server.Core.Extensions
         /// <returns>rouble amount</returns>
         private static double GetContainerRoubleTotalByLevel(
             int botLevel,
-            List<MinMaxLootValue> containerLootValuesPool
+            IEnumerable<MinMaxLootValue> containerLootValuesPool
         )
         {
             var matchingValue = containerLootValuesPool.FirstOrDefault(minMaxValue =>
diff --git a/Libraries/SPTarkov.Server.Core/Extensions/ProfileExtensions.cs b/Libraries/SPTarkov.Server.Core/Extensions/ProfileExtensions.cs
index 3fcb7a5e..80e5f40f 100644
--- a/Libraries/SPTarkov.Server.Core/Extensions/ProfileExtensions.cs
+++ b/Libraries/SPTarkov.Server.Core/Extensions/ProfileExtensions.cs
@@ -12,7 +12,7 @@ namespace SPTarkov.Server.Core.Extensions
         /// </summary>
         /// <param name="profile">Profile to get quest items from</param>
         /// <returns>List of item objects</returns>
-        public static List<Item> GetQuestItemsInProfile(this PmcData profile)
+        public static IEnumerable<Item> GetQuestItemsInProfile(this PmcData profile)
         {
             return profile
                 ?.Inventory?.Items.Where(i => i.ParentId == profile.Inventory.QuestRaidItems)
diff --git a/Libraries/SPTarkov.Server.Core/Extensions/QuestConditionExtensions.cs b/Libraries/SPTarkov.Server.Core/Extensions/QuestConditionExtensions.cs
index 2edfa902..9d2a3a5e 100644
--- a/Libraries/SPTarkov.Server.Core/Extensions/QuestConditionExtensions.cs
+++ b/Libraries/SPTarkov.Server.Core/Extensions/QuestConditionExtensions.cs
@@ -11,7 +11,7 @@ namespace SPTarkov.Server.Core.Extensions
         /// <param name="furtherFilter">OPTIONAL - Additional filter code to run</param>
         /// <returns></returns>
         public static List<QuestCondition> GetQuestConditions(
-            this List<QuestCondition> questConditions,
+            this IEnumerable<QuestCondition> questConditions,
             Func<QuestCondition, List<QuestCondition>>? furtherFilter = null
         )
         {
@@ -19,7 +19,7 @@ namespace SPTarkov.Server.Core.Extensions
         }
 
         public static List<QuestCondition> GetLevelConditions(
-            this List<QuestCondition> questConditions,
+            this IEnumerable<QuestCondition> questConditions,
             Func<QuestCondition, List<QuestCondition>>? furtherFilter = null
         )
         {
@@ -27,7 +27,7 @@ namespace SPTarkov.Server.Core.Extensions
         }
 
         public static List<QuestCondition> GetLoyaltyConditions(
-            this List<QuestCondition> questConditions,
+            this IEnumerable<QuestCondition> questConditions,
             Func<QuestCondition, List<QuestCondition>>? furtherFilter = null
         )
         {
@@ -35,7 +35,7 @@ namespace SPTarkov.Server.Core.Extensions
         }
 
         public static List<QuestCondition> GetStandingConditions(
-            this List<QuestCondition> questConditions,
+            this IEnumerable<QuestCondition> questConditions,
             Func<QuestCondition, List<QuestCondition>>? furtherFilter = null
         )
         {
@@ -43,7 +43,7 @@ namespace SPTarkov.Server.Core.Extensions
         }
 
         private static List<QuestCondition> FilterConditions(
-            List<QuestCondition> questConditions,
+            IEnumerable<QuestCondition> questConditions,
             string questType,
             Func<QuestCondition, List<QuestCondition>>? furtherFilter = null
         )
diff --git a/Libraries/SPTarkov.Server.Core/Generators/BotGenerator.cs b/Libraries/SPTarkov.Server.Core/Generators/BotGenerator.cs
index e385137b..4103e0a8 100644
--- a/Libraries/SPTarkov.Server.Core/Generators/BotGenerator.cs
+++ b/Libraries/SPTarkov.Server.Core/Generators/BotGenerator.cs
@@ -631,9 +631,9 @@ public class BotGenerator(
     /// </summary>
     /// <param name="bodyParts">Body parts</param>
     /// <returns>Part with the lowest hp</returns>
-    protected BodyPart? GetLowestHpBodyPart(List<BodyPart> bodyParts)
+    protected BodyPart? GetLowestHpBodyPart(IEnumerable<BodyPart> bodyParts)
     {
-        if (bodyParts.Count == 0)
+        if (!bodyParts.Any())
         {
             return null;
         }
diff --git a/Libraries/SPTarkov.Server.Core/Generators/BotInventoryGenerator.cs b/Libraries/SPTarkov.Server.Core/Generators/BotInventoryGenerator.cs
index a7f4acb7..908b6d99 100644
--- a/Libraries/SPTarkov.Server.Core/Generators/BotInventoryGenerator.cs
+++ b/Libraries/SPTarkov.Server.Core/Generators/BotInventoryGenerator.cs
@@ -732,7 +732,7 @@ public class BotInventoryGenerator(
     /// </summary>
     /// <param name="equipmentChances">Chances bot has certain equipment</param>
     /// <returns>What slots bot should have weapons generated for</returns>
-    public List<DesiredWeapons> GetDesiredWeaponsForBot(Chances equipmentChances)
+    public IEnumerable<DesiredWeapons> GetDesiredWeaponsForBot(Chances equipmentChances)
     {
         var shouldSpawnPrimary = randomUtil.GetChance100(
             equipmentChances.EquipmentChances["FirstPrimaryWeapon"]
diff --git a/Libraries/SPTarkov.Server.Core/Generators/BotLootGenerator.cs b/Libraries/SPTarkov.Server.Core/Generators/BotLootGenerator.cs
index 5d268182..c9d267c2 100644
--- a/Libraries/SPTarkov.Server.Core/Generators/BotLootGenerator.cs
+++ b/Libraries/SPTarkov.Server.Core/Generators/BotLootGenerator.cs
@@ -667,7 +667,7 @@ public class BotLootGenerator(
     /// </summary>
     /// <param name="walletId"> Wallet to add loot to</param>
     /// <returns>Generated list of currency stacks with the wallet as their parent</returns>
-    public List<List<Item>> CreateWalletLoot(string walletId)
+    public List<List<Item>> CreateWalletLoot(MongoId walletId)
     {
         List<List<Item>> result = [];
 
diff --git a/Libraries/SPTarkov.Server.Core/Generators/BotWeaponGenerator.cs b/Libraries/SPTarkov.Server.Core/Generators/BotWeaponGenerator.cs
index 3a62c462..8093ee96 100644
--- a/Libraries/SPTarkov.Server.Core/Generators/BotWeaponGenerator.cs
+++ b/Libraries/SPTarkov.Server.Core/Generators/BotWeaponGenerator.cs
@@ -156,12 +156,13 @@ public class BotWeaponGenerator(
 
         // Create with just base weapon item
         var weaponWithModsArray = ConstructWeaponBaseList(
-            weaponTpl,
-            weaponParentId,
-            slotName,
-            weaponItemTemplate,
-            botRole
-        );
+                weaponTpl,
+                weaponParentId,
+                slotName,
+                weaponItemTemplate,
+                botRole
+            )
+            .ToList();
 
         // Chance to add randomised weapon enhancement
         if (isPmc && randomUtil.GetChance100(_pmcConfig.WeaponHasEnhancementChancePercent))
@@ -276,7 +277,7 @@ public class BotWeaponGenerator(
     protected void AddCartridgeToChamber(
         List<Item> weaponWithModsList,
         MongoId ammoTemplate,
-        List<string> chamberSlotIds
+        IEnumerable<string> chamberSlotIds
     )
     {
         foreach (var slotId in chamberSlotIds)
@@ -315,7 +316,7 @@ public class BotWeaponGenerator(
     /// <param name="weaponItemTemplate">Database template for weapon</param>
     /// <param name="botRole">For durability values</param>
     /// <returns>Base weapon item in a list</returns>
-    protected List<Item> ConstructWeaponBaseList(
+    protected IEnumerable<Item> ConstructWeaponBaseList(
         MongoId weaponTemplate,
         string weaponParentId,
         string equipmentSlot,
@@ -405,7 +406,7 @@ public class BotWeaponGenerator(
     /// <param name="weaponItemList">Weapon + mods</param>
     /// <param name="botRole">Role of bot weapon is for</param>
     /// <returns>True if valid</returns>
-    protected bool IsWeaponValid(List<Item> weaponItemList, string botRole)
+    protected bool IsWeaponValid(IEnumerable<Item> weaponItemList, string botRole)
     {
         foreach (var mod in weaponItemList)
         {
@@ -878,12 +879,12 @@ public class BotWeaponGenerator(
         }
 
         // Magazine, usually
-        var parentItem = itemHelper.GetItem(magazineTemplate.Parent).Value;
+        var parentDbItem = itemHelper.GetItem(magazineTemplate.Parent).Value;
 
         // Revolver shotgun (MTs-255-12) uses a magazine with chambers, not cartridges ("camora_xxx")
         // Exchange of the camora ammo is not necessary we could also just check for stackSize > 0 here
         // and remove the else
-        if (botWeaponGeneratorHelper.MagazineIsCylinderRelated(parentItem.Name))
+        if (botWeaponGeneratorHelper.MagazineIsCylinderRelated(parentDbItem.Name))
         {
             FillCamorasWithAmmo(weaponMods, magazine.Id, cartridgeTemplate);
         }
@@ -904,9 +905,9 @@ public class BotWeaponGenerator(
     /// <param name="weaponMods">Weapon with children.</param>
     /// <param name="ubglMod">Underbarrrel grenade launcher item.</param>
     /// <param name="ubglAmmoTpl">Grenade ammo template.</param>
-    protected void FillUbgl(List<Item> weaponMods, Item ubglMod, MongoId ubglAmmoTpl)
+    protected void FillUbgl(IEnumerable<Item> weaponMods, Item ubglMod, MongoId ubglAmmoTpl)
     {
-        weaponMods.Add(
+        weaponMods.Append(
             new Item
             {
                 Id = new MongoId(),
@@ -975,7 +976,11 @@ public class BotWeaponGenerator(
     /// <param name="weaponMods">Weapon mods to find and update camora mod(s) from</param>
     /// <param name="magazineId">Magazine id to find and add to</param>
     /// <param name="ammoTpl">Ammo template id to hydrate with</param>
-    protected void FillCamorasWithAmmo(List<Item> weaponMods, MongoId magazineId, MongoId ammoTpl)
+    protected void FillCamorasWithAmmo(
+        IEnumerable<Item> weaponMods,
+        MongoId magazineId,
+        MongoId ammoTpl
+    )
     {
         // for CylinderMagazine we exchange the ammo in the "camoras".
         // This might not be necessary since we already filled the camoras with a random whitelisted and compatible ammo type,
diff --git a/Libraries/SPTarkov.Server.Core/Helpers/BotGeneratorHelper.cs b/Libraries/SPTarkov.Server.Core/Helpers/BotGeneratorHelper.cs
index 375ac726..9a264c77 100644
--- a/Libraries/SPTarkov.Server.Core/Helpers/BotGeneratorHelper.cs
+++ b/Libraries/SPTarkov.Server.Core/Helpers/BotGeneratorHelper.cs
@@ -318,7 +318,7 @@ public class BotGeneratorHelper(
     /// <param name="equipmentSlot">Slot the item will be placed into</param>
     /// <returns>false if no incompatibilities, also has incompatibility reason</returns>
     public ChooseRandomCompatibleModResult IsItemIncompatibleWithCurrentItems(
-        List<Item> itemsEquipped,
+        IEnumerable<Item> itemsEquipped,
         MongoId tplToCheck,
         string equipmentSlot
     )
@@ -335,9 +335,10 @@ public class BotGeneratorHelper(
         }
 
         // TODO: Can probably be optimized to cache itemTemplates as items are added to inventory
-        var equippedItemsDb = itemsEquipped
-            .Select(equippedItem => itemHelper.GetItem(equippedItem.Template).Value)
-            .ToList();
+        var equippedItemsDb = itemsEquipped.Select(equippedItem =>
+            itemHelper.GetItem(equippedItem.Template).Value
+        );
+
         var (itemIsValid, itemToEquip) = itemHelper.GetItem(tplToCheck);
 
         if (!itemIsValid)
@@ -380,7 +381,7 @@ public class BotGeneratorHelper(
         }
 
         // Does an equipped item have a property that blocks the desired item - check for prop "BlocksX" .e.g BlocksEarpiece / BlocksFaceCover
-        var templateItems = equippedItemsDb.ToList();
+        var templateItems = equippedItemsDb;
         var blockingItem = templateItems.FirstOrDefault(item =>
             HasBlockingProperty(item, equipmentSlot)
         );
@@ -542,7 +543,7 @@ public class BotGeneratorHelper(
         HashSet<EquipmentSlots> equipmentSlots,
         MongoId rootItemId,
         MongoId rootItemTplId,
-        List<Item> itemWithChildren,
+        IEnumerable<Item> itemWithChildren,
         BotBaseInventory inventory,
         HashSet<string>? containersIdFull = null
     )
@@ -718,7 +719,7 @@ public class BotGeneratorHelper(
     /// <returns></returns>
     protected List<Item> GetContainerItemsWithChildren(
         IEnumerable<Item> containerRootItems,
-        List<Item> inventoryItems
+        IEnumerable<Item> inventoryItems
     )
     {
         var result = new List<Item>();
@@ -729,7 +730,7 @@ public class BotGeneratorHelper(
         }
 
         // Filter out all items without location prop, (child items)
-        var itemsWithoutLocation = inventoryItems.Where(item => item.Location is null).ToList();
+        var itemsWithoutLocation = inventoryItems.Where(item => item.Location is null);
         foreach (var rootItem in containerRootItems)
         {
             // Check item in container for children, store for later insertion into `containerItemsToCheck`
diff --git a/Libraries/SPTarkov.Server.Core/Helpers/InventoryHelper.cs b/Libraries/SPTarkov.Server.Core/Helpers/InventoryHelper.cs
index 83938713..71cb0eb3 100644
--- a/Libraries/SPTarkov.Server.Core/Helpers/InventoryHelper.cs
+++ b/Libraries/SPTarkov.Server.Core/Helpers/InventoryHelper.cs
@@ -172,7 +172,7 @@ public class InventoryHelper(
     /// </summary>
     /// <param name="itemWithChildren">An item</param>
     /// <param name="foundInRaid">Item was found in raid</param>
-    protected void SetFindInRaidStatusForItem(List<Item> itemWithChildren, bool foundInRaid)
+    protected void SetFindInRaidStatusForItem(IEnumerable<Item> itemWithChildren, bool foundInRaid)
     {
         foreach (var item in itemWithChildren)
         {
@@ -214,7 +214,10 @@ public class InventoryHelper(
     /// <param name="sessionId">Player id</param>
     /// <param name="itemsWithChildren">Array of items with children to try and fit</param>
     /// <returns>True all items fit</returns>
-    public bool CanPlaceItemsInInventory(MongoId sessionId, List<List<Item>> itemsWithChildren)
+    public bool CanPlaceItemsInInventory(
+        MongoId sessionId,
+        IEnumerable<List<Item>> itemsWithChildren
+    )
     {
         var pmcData = profileHelper.GetPmcProfile(sessionId);
 
@@ -238,7 +241,10 @@ public class InventoryHelper(
     /// <param name="containerFS2D">Container grid to fit items into</param>
     /// <param name="itemsWithChildren">Items to try and fit into grid</param>
     /// <returns>True all fit</returns>
-    public bool CanPlaceItemsInContainer(int[,] containerFS2D, List<List<Item>> itemsWithChildren)
+    public bool CanPlaceItemsInContainer(
+        int[,] containerFS2D,
+        IEnumerable<List<Item>> itemsWithChildren
+    )
     {
         return itemsWithChildren.All(itemWithChildren =>
             CanPlaceItemInContainer(containerFS2D, itemWithChildren)
@@ -665,7 +671,7 @@ public class InventoryHelper(
     /// <param name="itemId">Items id to get size of</param>
     /// <param name="inventoryItems"></param>
     /// <returns>[width, height]</returns>
-    public (int, int) GetItemSize(MongoId itemTpl, MongoId itemId, List<Item> inventoryItems)
+    public (int, int) GetItemSize(MongoId itemTpl, MongoId itemId, IEnumerable<Item> inventoryItems)
     {
         // -> Prepares item Width and height returns [sizeX, sizeY]
         return GetSizeByInventoryItemHash(itemTpl, itemId, inventoryItems.GetInventoryItemHash());
@@ -859,7 +865,7 @@ public class InventoryHelper(
     public int[,] GetContainerMap(
         int containerSizeHorizontalX,
         int containerSizeVerticalY,
-        List<Item> itemList,
+        IEnumerable<Item> itemList,
         MongoId containerId
     )
     {
@@ -1179,7 +1185,7 @@ public class InventoryHelper(
     /// <returns>True if move was successful</returns>
     public bool MoveItemInternal(
         PmcData pmcData,
-        List<Item> inventoryItems,
+        IEnumerable<Item> inventoryItems,
         InventoryMoveRequestData moveRequest,
         out string errorMessage
     )
@@ -1193,18 +1199,18 @@ public class InventoryHelper(
         );
         if (matchingInventoryItem is null)
         {
-            var noMatchingItemMesage =
+            var noMatchingItemMessage =
                 $"Unable to move item: {moveRequest.Item}, cannot find in inventory";
-            logger.Error(noMatchingItemMesage);
+            logger.Error(noMatchingItemMessage);
 
-            errorMessage = noMatchingItemMesage;
+            errorMessage = noMatchingItemMessage;
             return false;
         }
 
         if (logger.IsLogEnabled(LogLevel.Debug))
         {
             logger.Debug(
-                $"{moveRequest.Action} item: {moveRequest.Item} from slotid: {matchingInventoryItem.SlotId} to container: {moveRequest.To.Container}"
+                $"{moveRequest.Action} item: {moveRequest.Item} from slotId: {matchingInventoryItem.SlotId} to container: {moveRequest.To.Container}"
             );
         }
 
@@ -1291,7 +1297,7 @@ public class InventoryHelper(
     /// </summary>
     /// <param name="items"></param>
     /// <param name="request"></param>
-    protected void HandleCartridgeMove(List<Item> items, InventoryMoveRequestData request)
+    protected void HandleCartridgeMove(IEnumerable<Item> items, InventoryMoveRequestData request)
     {
         // Not moving item into a cartridge slot, skip
         if (request.To.Container != "cartridges")
@@ -1326,7 +1332,7 @@ public class InventoryHelper(
         return _inventoryConfig;
     }
 
-    public void ValidateInventoryUsesMongoIds(List<Item> itemsToValidate)
+    public void ValidateInventoryUsesMongoIds(IEnumerable<Item> itemsToValidate)
     {
         var errors = itemsToValidate
             .Where(item => !item.Id.IsValidMongoId())
diff --git a/Libraries/SPTarkov.Server.Core/Helpers/ItemHelper.cs b/Libraries/SPTarkov.Server.Core/Helpers/ItemHelper.cs
index c8245085..64f73bd4 100644
--- a/Libraries/SPTarkov.Server.Core/Helpers/ItemHelper.cs
+++ b/Libraries/SPTarkov.Server.Core/Helpers/ItemHelper.cs
@@ -566,13 +566,13 @@ public class ItemHelper(
     /// <param name="skipArmorItemsWithoutDurability">Skip over armor items without durability</param>
     /// <returns>% quality modifier between 0 and 1</returns>
     public double GetItemQualityModifierForItems(
-        List<Item> itemWithChildren,
+        IEnumerable<Item> itemWithChildren,
         bool skipArmorItemsWithoutDurability = false
     )
     {
-        if (IsOfBaseclass(itemWithChildren[0].Template, BaseClasses.WEAPON))
+        if (IsOfBaseclass(itemWithChildren.First().Template, BaseClasses.WEAPON))
         {
-            return Math.Round(GetItemQualityModifier(itemWithChildren[0]), 5);
+            return Math.Round(GetItemQualityModifier(itemWithChildren.First()), 5);
         }
 
         var qualityModifier = 0D;
@@ -1712,13 +1712,12 @@ public class ItemHelper(
     /// </summary>
     /// <param name="desiredBaseType">Item base type wanted</param>
     /// <returns>Array of tpls</returns>
-    public List<MongoId> GetItemTplsOfBaseType(string desiredBaseType)
+    public IEnumerable<MongoId> GetItemTplsOfBaseType(string desiredBaseType)
     {
         return databaseService
             .GetItems()
             .Values.Where(item => item.Parent == desiredBaseType)
-            .Select(item => item.Id)
-            .ToList();
+            .Select(item => item.Id);
     }
 
     /// <summary>
diff --git a/Libraries/SPTarkov.Server.Core/Services/BotWeaponModLimitService.cs b/Libraries/SPTarkov.Server.Core/Services/BotWeaponModLimitService.cs
index 50b63c01..80ce2054 100644
--- a/Libraries/SPTarkov.Server.Core/Services/BotWeaponModLimitService.cs
+++ b/Libraries/SPTarkov.Server.Core/Services/BotWeaponModLimitService.cs
@@ -68,7 +68,7 @@ public class BotWeaponModLimitService(
         TemplateItem modTemplate,
         BotModLimits modLimits,
         TemplateItem modsParent,
-        List<Item> weapon
+        IEnumerable<Item> weapon
     )
     {
         // If mod or mods parent is the NcSTAR MPR45 Backup mount, allow it as it looks cool
@@ -115,11 +115,11 @@ public class BotWeaponModLimitService(
             );
         }
 
-        // Don't allow multple mounts on a weapon (except when mount is on another mount)
+        // Don't allow multiple mounts on a weapon (except when mount is on another mount)
         // Fail when:
         // Over or at scope limit on weapon
         // Item being added is a mount but the parent item is NOT a mount (Allows red dot sub-mounts on mounts)
-        // Mount has one slot and its for a mod_scope
+        // Mount has one slot and it is for a mod_scope
         if (
             modLimits.Scope.Count >= modLimits.ScopeMax
             && modTemplate.Properties.Slots?.Count == 1
diff --git a/Libraries/SPTarkov.Server.Core/Services/FenceService.cs b/Libraries/SPTarkov.Server.Core/Services/FenceService.cs
index 88031874..e6b15920 100644
--- a/Libraries/SPTarkov.Server.Core/Services/FenceService.cs
+++ b/Libraries/SPTarkov.Server.Core/Services/FenceService.cs
@@ -187,7 +187,7 @@ public class FenceService(
     /// <param name="itemTpl"> The item tpl to calculate the fence price for </param>
     /// <param name="items"> The items (with its children) to calculate fence price for </param>
     /// <returns> Price of the item for Fence </returns>
-    public double? GetItemPrice(MongoId itemTpl, List<Item> items)
+    public double? GetItemPrice(MongoId itemTpl, IEnumerable<Item> items)
     {
         return itemHelper.IsOfBaseclass(itemTpl, BaseClasses.AMMO_BOX)
             ? GetAmmoBoxPrice(items) * traderConfig.Fence.ItemPriceMult
@@ -200,7 +200,7 @@ public class FenceService(
     /// </summary>
     /// <param name="items"> The ammo box (and all its children ammo items) </param>
     /// <returns> The price of the ammo box </returns>
-    protected double? GetAmmoBoxPrice(List<Item> items)
+    protected double? GetAmmoBoxPrice(IEnumerable<Item> items)
     {
         double? total = 0D;
         foreach (var item in items)
@@ -478,7 +478,7 @@ public class FenceService(
     /// <param name="generationValues"> Base counts assorts should be adjusted to </param>
     /// <returns> GenerationAssortValues object with adjustments needed to reach desired state </returns>
     protected GenerationAssortValues GetItemCountsToGenerate(
-        List<Item> assortItems,
+        IEnumerable<Item> assortItems,
         GenerationAssortValues generationValues
     )
     {
@@ -546,7 +546,7 @@ public class FenceService(
     /// </summary>
     /// <param name="assort"> Trader assort to remove item from </param>
     /// <param name="rootItems"> Pool of root items to pick from to remove </param>
-    protected void RemoveRandomItemFromAssorts(TraderAssort assort, List<Item> rootItems)
+    protected void RemoveRandomItemFromAssorts(TraderAssort assort, IEnumerable<Item> rootItems)
     {
         // Pick a random root item to remove from Fence
         var rootItemToAdjust = randomUtil.GetArrayValue(rootItems);
@@ -923,7 +923,7 @@ public class FenceService(
     protected Item? GetMatchingItem(
         Item rootItemBeingAdded,
         TemplateItem itemDbDetails,
-        List<List<Item>> itemsWithChildren
+        IEnumerable<List<Item>> itemsWithChildren
     )
     {
         // Get matching root items
@@ -967,7 +967,7 @@ public class FenceService(
                 && rootItemBeingAdded.Upd?.MedKit?.HpResource == item.Upd?.MedKit?.HpResource
             )
             // e.g. bandages with multiple use
-            // Both undefined === both max resoruce left
+            // Both undefined === both max resource left
             {
                 return item;
             }
@@ -1243,7 +1243,7 @@ public class FenceService(
     /// </summary>
     /// <param name="armor"> Armor item array to add mods into </param>
     /// <param name="itemDbDetails"> Armor items db template </param>
-    protected void RandomiseArmorModDurability(List<Item> armor, TemplateItem itemDbDetails)
+    protected void RandomiseArmorModDurability(IEnumerable<Item> armor, TemplateItem itemDbDetails)
     {
         // Armor has no mods, nothing to randomise
         if (itemDbDetails.Properties.Slots == null)
@@ -1251,20 +1251,18 @@ public class FenceService(
             return;
         }
 
-        // Check for and adjust soft insert durability values
-        var requiredSlots = itemDbDetails
-            .Properties.Slots?.Where(slot => slot.Required ?? false)
-            .ToList();
-        if ((requiredSlots?.Count ?? 0) > 1)
+        var requiredSlots = itemDbDetails.Properties.Slots?.Where(slot => slot.Required ?? false);
+        if (requiredSlots is not null && requiredSlots.Any())
         {
+            // Has soft inserts, randomise
             RandomiseArmorSoftInsertDurabilities(requiredSlots, armor);
         }
 
         // Check for and adjust plate durability values
-        var plateSlots = itemDbDetails
-            .Properties.Slots?.Where(slot => itemHelper.IsRemovablePlateSlot(slot.Name))
-            .ToList();
-        if ((plateSlots?.Count ?? 0) > 1)
+        var plateSlots = itemDbDetails.Properties.Slots?.Where(slot =>
+            itemHelper.IsRemovablePlateSlot(slot.Name)
+        );
+        if (plateSlots is not null && plateSlots.Any())
         {
             RandomiseArmorInsertsDurabilities(plateSlots, armor);
         }
@@ -1276,8 +1274,8 @@ public class FenceService(
     /// <param name="softInsertSlots"> Slots of items to randomise </param>
     /// <param name="armorItemAndMods"> Array of armor + inserts to get items from </param>
     protected void RandomiseArmorSoftInsertDurabilities(
-        List<Slot> softInsertSlots,
-        List<Item> armorItemAndMods
+        IEnumerable<Slot> softInsertSlots,
+        IEnumerable<Item> armorItemAndMods
     )
     {
         foreach (var requiredSlot in softInsertSlots)
@@ -1308,7 +1306,7 @@ public class FenceService(
 
             itemHelper.AddUpdObjectToItem(modItemToAdjust);
 
-            // Ensure property isn't null
+            // Fence assorts can be null, ensure they have defaults
             modItemToAdjust.Upd.Repairable ??= new UpdRepairable
             {
                 Durability = modItemDbDetails.Properties.MaxDurability,
@@ -1343,8 +1341,8 @@ public class FenceService(
     /// <param name="plateSlots"> Slots of items to randomise </param>
     /// <param name="armorItemAndMods"> Array of armor + inserts to get items from </param>
     protected void RandomiseArmorInsertsDurabilities(
-        List<Slot> plateSlots,
-        List<Item> armorItemAndMods
+        IEnumerable<Slot> plateSlots,
+        IEnumerable<Item> armorItemAndMods
     )
     {
         foreach (var plateSlot in plateSlots)
@@ -1356,8 +1354,6 @@ public class FenceService(
                 continue;
             }
 
-            var armorWithMods = armorItemAndMods;
-
             var modItemDbDetails = itemHelper.GetItem(plateTpl.Value).Value;
 
             // Chance to remove plate
@@ -1386,14 +1382,14 @@ public class FenceService(
             );
 
             // Find items mod to apply durability changes to
-            var modItemToAdjust = armorWithMods.FirstOrDefault(mod =>
+            var modItemToAdjust = armorItemAndMods.FirstOrDefault(mod =>
                 string.Equals(mod.SlotId, plateSlot.Name, StringComparison.OrdinalIgnoreCase)
             );
 
             if (modItemToAdjust == null)
             {
                 logger.Warning(
-                    $"Unable to randomise armor items {armorWithMods[0].Template} {plateSlot.Name} slot as it cannot be found, skipping"
+                    $"Unable to randomise armor items {armorItemAndMods.First().Template} {plateSlot.Name} slot as it cannot be found, skipping"
                 );
                 continue;
             }
diff --git a/Libraries/SPTarkov.Server.Core/Services/LocationLifecycleService.cs b/Libraries/SPTarkov.Server.Core/Services/LocationLifecycleService.cs
index 20c4d59a..ae611951 100644
--- a/Libraries/SPTarkov.Server.Core/Services/LocationLifecycleService.cs
+++ b/Libraries/SPTarkov.Server.Core/Services/LocationLifecycleService.cs
@@ -926,7 +926,7 @@ public class LocationLifecycleService(
 
         if (isDead)
         {
-            if (lostQuestItems.Count > 0)
+            if (lostQuestItems.Any())
             // MUST occur AFTER quests have post raid quest data has been merged "processPostRaidQuests()"
             // Player is dead + had quest items, check and fix any broken find item quests
             {
@@ -981,8 +981,8 @@ public class LocationLifecycleService(
     /// <param name="profileQuests"> Quest status data from player profile </param>
     protected void CheckForAndFixPickupQuestsAfterDeath(
         MongoId sessionId,
-        List<Item> lostQuestItems,
-        List<QuestStatus> profileQuests
+        IEnumerable<Item> lostQuestItems,
+        IEnumerable<QuestStatus> profileQuests
     )
     {
         // Exclude completed quests
diff --git a/Libraries/SPTarkov.Server.Core/Services/MailSendService.cs b/Libraries/SPTarkov.Server.Core/Services/MailSendService.cs
index 513a0174..e78b29b8 100644
--- a/Libraries/SPTarkov.Server.Core/Services/MailSendService.cs
+++ b/Libraries/SPTarkov.Server.Core/Services/MailSendService.cs
@@ -117,7 +117,7 @@ public class MailSendService(
         MongoId? trader,
         MessageType messageType,
         string messageLocaleId,
-        List<Item>? items,
+        IEnumerable<Item>? items,
         long? maxStorageTimeSeconds = 172800,
         SystemData? systemData = null,
         MessageContentRagfair? ragfair = null
@@ -145,9 +145,8 @@ public class MailSendService(
             Items = [],
         };
 
-        // add items to message
-
-        if (items?.Count > 0)
+        // Add items to message
+        if (items is not null && items.Any())
         {
             details.Items.AddRange(items);
             details.ItemsMaxStorageLifetimeSeconds =