diff --git a/Libraries/SPTarkov.Server.Core/Generators/LootGenerator.cs b/Libraries/SPTarkov.Server.Core/Generators/LootGenerator.cs
index 49298738..58afe175 100644
--- a/Libraries/SPTarkov.Server.Core/Generators/LootGenerator.cs
+++ b/Libraries/SPTarkov.Server.Core/Generators/LootGenerator.cs
@@ -36,9 +36,10 @@ public class LootGenerator(
     /// </summary>
     /// <param name="options">parameters to adjust how loot is generated</param>
     /// <returns>An array of loot items</returns>
-    public List<List<Item>> CreateRandomLoot(LootRequest options)
+    public IEnumerable<List<Item>> CreateRandomLoot(LootRequest options)
     {
         var result = new List<List<Item>>();
+
         var itemTypeCounts = InitItemLimitCounter(options.ItemLimits);
 
         // Handle sealed weapon containers
@@ -81,7 +82,7 @@ public class LootGenerator(
         );
 
         // Pool has items we could add as loot, proceed
-        if (rewardPoolResults.ItemPool.Count > 0)
+        if (rewardPoolResults.ItemPool.Any())
         {
             var randomisedItemCount = randomUtil.GetInt(
                 options.ItemCount.Min,
@@ -113,11 +114,9 @@ public class LootGenerator(
         );
         if (randomisedWeaponPresetCount > 0)
         {
-            var weaponDefaultPresets = globalDefaultPresets
-                .Where(preset =>
-                    itemHelper.IsOfBaseclass(preset.Encyclopedia.Value, BaseClasses.WEAPON)
-                )
-                .ToList();
+            var weaponDefaultPresets = globalDefaultPresets.Where(preset =>
+                itemHelper.IsOfBaseclass(preset.Encyclopedia.Value, BaseClasses.WEAPON)
+            );
 
             if (weaponDefaultPresets.Any())
             {
@@ -149,9 +148,9 @@ public class LootGenerator(
             var armorDefaultPresets = globalDefaultPresets.Where(preset =>
                 itemHelper.ArmorItemCanHoldMods(preset.Encyclopedia.Value)
             );
-            var levelFilteredArmorPresets = armorDefaultPresets
-                .Where(armor => IsArmorOfDesiredProtectionLevel(armor, options))
-                .ToList();
+            var levelFilteredArmorPresets = armorDefaultPresets.Where(armor =>
+                IsArmorOfDesiredProtectionLevel(armor, options)
+            );
 
             // Add some armors to rewards
             if (levelFilteredArmorPresets.Any())
@@ -245,7 +244,7 @@ public class LootGenerator(
     /// <returns>results of filtering + blacklist used</returns>
     protected ItemRewardPoolResults GetItemRewardPool(
         HashSet<MongoId> itemTplBlacklist,
-        List<MongoId> itemTypeWhitelist,
+        HashSet<MongoId> itemTypeWhitelist,
         bool useRewardItemBlacklist,
         bool allowBossItems,
         bool blockSeasonalItemsOutOfSeason
@@ -281,14 +280,12 @@ public class LootGenerator(
             itemBlacklist.UnionWith(seasonalEventService.GetInactiveSeasonalEventItems());
         }
 
-        var items = itemsDb
-            .Where(item =>
-                !itemBlacklist.Contains(item.Id)
-                && string.Equals(item.Type, "item", StringComparison.OrdinalIgnoreCase)
-                && !item.Properties.QuestItem.GetValueOrDefault(false)
-                && itemTypeWhitelist.Contains(item.Parent)
-            )
-            .ToList();
+        var items = itemsDb.Where(item =>
+            !itemBlacklist.Contains(item.Id)
+            && string.Equals(item.Type, "item", StringComparison.OrdinalIgnoreCase)
+            && !item.Properties.QuestItem.GetValueOrDefault(false)
+            && itemTypeWhitelist.Contains(item.Parent)
+        );
 
         return new ItemRewardPoolResults { ItemPool = items, Blacklist = itemBlacklist };
     }
@@ -348,7 +345,7 @@ public class LootGenerator(
     /// <param name="result">array to add found item to</param>
     /// <returns>true if item was valid and added to pool</returns>
     protected bool FindAndAddRandomItemToLoot(
-        List<TemplateItem> items,
+        IEnumerable<TemplateItem> items,
         Dictionary<MongoId, ItemLimit> itemTypeCounts,
         LootRequest options,
         List<List<Item>> result
@@ -426,13 +423,13 @@ public class LootGenerator(
     /// <param name="result">List to add chosen preset to</param>
     /// <returns>true if preset was valid and added to pool</returns>
     protected bool FindAndAddRandomPresetToLoot(
-        List<Preset> presetPool,
+        IEnumerable<Preset> presetPool,
         Dictionary<MongoId, ItemLimit> itemTypeCounts,
         HashSet<MongoId> itemBlacklist,
         List<List<Item>> result
     )
     {
-        if (presetPool.Count == 0)
+        if (!presetPool.Any())
         {
             logger.Warning(serverLocalisationService.GetText("loot-preset_pool_is_empty"));
 
@@ -732,10 +729,10 @@ public class LootGenerator(
             // Find a random item of the desired type and add as reward
             for (var index = 0; index < rewardCount; index++)
             {
-                var chosenItem = randomUtil.DrawRandomFromList(relatedItems.ToList());
+                var chosenItem = randomUtil.GetArrayValue(relatedItems);
                 var reward = new List<Item>
                 {
-                    new() { Id = new MongoId(), Template = chosenItem[0].Id },
+                    new() { Id = new MongoId(), Template = chosenItem.Id },
                 };
 
                 modRewards.Add(reward);
@@ -785,7 +782,7 @@ public class LootGenerator(
     /// </summary>
     /// <param name="rewardContainerDetails"></param>
     /// <returns>Single tpl</returns>
-    protected string PickRewardItem(RewardDetails rewardContainerDetails)
+    protected MongoId PickRewardItem(RewardDetails rewardContainerDetails)
     {
         if (
             rewardContainerDetails.RewardTplPool is not null
@@ -803,7 +800,7 @@ public class LootGenerator(
 
     protected record ItemRewardPoolResults
     {
-        public List<TemplateItem> ItemPool { get; set; }
+        public IEnumerable<TemplateItem> ItemPool { get; set; }
 
         public HashSet<MongoId> Blacklist { get; set; }
     }
diff --git a/Libraries/SPTarkov.Server.Core/Models/Eft/Location/GetAirdropLootResponse.cs b/Libraries/SPTarkov.Server.Core/Models/Eft/Location/GetAirdropLootResponse.cs
index 89607980..d03bf129 100644
--- a/Libraries/SPTarkov.Server.Core/Models/Eft/Location/GetAirdropLootResponse.cs
+++ b/Libraries/SPTarkov.Server.Core/Models/Eft/Location/GetAirdropLootResponse.cs
@@ -13,8 +13,8 @@ public record GetAirdropLootResponse
     ///     The type of airdrop
     /// </summary>
     [JsonPropertyName("icon")]
-    public AirdropTypeEnum? Icon { get; set; }
+    public AirdropTypeEnum Icon { get; set; }
 
     [JsonPropertyName("container")]
-    public List<Item>? Container { get; set; }
+    public IEnumerable<Item> Container { get; set; }
 }
diff --git a/Libraries/SPTarkov.Server.Core/Models/Spt/Config/AirdropConfig.cs b/Libraries/SPTarkov.Server.Core/Models/Spt/Config/AirdropConfig.cs
index 38e4ce2f..683b3c39 100644
--- a/Libraries/SPTarkov.Server.Core/Models/Spt/Config/AirdropConfig.cs
+++ b/Libraries/SPTarkov.Server.Core/Models/Spt/Config/AirdropConfig.cs
@@ -68,7 +68,7 @@ public record AirdropLoot
     ///     Item type (parentId) to allow inside crate
     /// </summary>
     [JsonPropertyName("itemTypeWhitelist")]
-    public required List<MongoId> ItemTypeWhitelist { get; set; }
+    public required HashSet<MongoId> ItemTypeWhitelist { get; set; }
 
     /// <summary>
     ///     Item type/ item tpls to limit count of inside crate - key: item base type: value: max count
diff --git a/Libraries/SPTarkov.Server.Core/Models/Spt/Config/InventoryConfig.cs b/Libraries/SPTarkov.Server.Core/Models/Spt/Config/InventoryConfig.cs
index 61e967ed..f52014a9 100644
--- a/Libraries/SPTarkov.Server.Core/Models/Spt/Config/InventoryConfig.cs
+++ b/Libraries/SPTarkov.Server.Core/Models/Spt/Config/InventoryConfig.cs
@@ -51,7 +51,7 @@ public record RewardDetails
     public Dictionary<MongoId, double>? RewardTplPool { get; set; }
 
     [JsonPropertyName("rewardTypePool")]
-    public List<MongoId>? RewardTypePool { get; set; }
+    public HashSet<MongoId>? RewardTypePool { get; set; }
 }
 
 public record SealedAirdropContainerSettings
diff --git a/Libraries/SPTarkov.Server.Core/Models/Spt/Services/LootRequest.cs b/Libraries/SPTarkov.Server.Core/Models/Spt/Services/LootRequest.cs
index 20f3e892..e5864c65 100644
--- a/Libraries/SPTarkov.Server.Core/Models/Spt/Services/LootRequest.cs
+++ b/Libraries/SPTarkov.Server.Core/Models/Spt/Services/LootRequest.cs
@@ -43,7 +43,7 @@ public record LootRequest
     ///     Item tpl whitelist to pick from
     /// </summary>
     [JsonPropertyName("itemTypeWhitelist")]
-    public List<MongoId>? ItemTypeWhitelist { get; set; }
+    public HashSet<MongoId>? ItemTypeWhitelist { get; set; }
 
     /// <summary>
     ///     key: item base type: value: max count
diff --git a/Libraries/SPTarkov.Server.Core/Services/AirdropService.cs b/Libraries/SPTarkov.Server.Core/Services/AirdropService.cs
index fcdbf5e0..3ab1c736 100644
--- a/Libraries/SPTarkov.Server.Core/Services/AirdropService.cs
+++ b/Libraries/SPTarkov.Server.Core/Services/AirdropService.cs
@@ -16,8 +16,8 @@ namespace SPTarkov.Server.Core.Services;
 
 [Injectable]
 public class AirdropService(
-    ConfigServer configServer,
     ISptLogger<AirdropService> _logger,
+    ConfigServer configServer,
     LootGenerator _lootGenerator,
     DatabaseService databaseService,
     WeightedRandomHelper _weightedRandomHelper,
@@ -80,14 +80,12 @@ public class AirdropService(
         // Filter loot pool to just items that fit crate
         var crateLoot = GetLootThatFitsContainer(airdropCrateItem, crateLootPool);
 
-        // Flatten loot into single array ready to be returned
-        var flattenedCrateLoot = crateLoot.SelectMany(x => x).ToList();
+        // Create new array with crate at front + loot behind
+        var containerWithLoot = Enumerable.Empty<Item>().Append(airdropCrateItem);
+        containerWithLoot = containerWithLoot.Union(crateLoot.SelectMany(x => x));
 
-        // Add crate to front of loot rewards
-        flattenedCrateLoot.Insert(0, airdropCrateItem);
-
-        // Re-parent loot items to crate we just added
-        foreach (var item in flattenedCrateLoot)
+        // Re-parent root loot items to have crate as parent
+        foreach (var item in containerWithLoot)
         {
             if (item.Id == airdropCrateItem.Id)
             // Crate itself, skip
@@ -105,8 +103,8 @@ public class AirdropService(
 
         return new GetAirdropLootResponse
         {
-            Icon = airdropConfig.Icon,
-            Container = flattenedCrateLoot,
+            Icon = airdropConfig.Icon.Value,
+            Container = containerWithLoot,
         };
     }
 
@@ -116,9 +114,9 @@ public class AirdropService(
     /// <param name="container">Crate item to fit items into</param>
     /// <param name="crateLootPool">Item pool to try and fit into container</param>
     /// <returns>Items that will fit container</returns>
-    protected List<List<Item>> GetLootThatFitsContainer(
+    protected IEnumerable<List<Item>> GetLootThatFitsContainer(
         Item container,
-        List<List<Item>> crateLootPool
+        IEnumerable<List<Item>> crateLootPool
     )
     {
         // list of root item + children in list
diff --git a/Libraries/SPTarkov.Server.Core/Services/LocationLifecycleService.cs b/Libraries/SPTarkov.Server.Core/Services/LocationLifecycleService.cs
index 44fc663a..cf0d9c5f 100644
--- a/Libraries/SPTarkov.Server.Core/Services/LocationLifecycleService.cs
+++ b/Libraries/SPTarkov.Server.Core/Services/LocationLifecycleService.cs
@@ -447,7 +447,7 @@ public class LocationLifecycleService(
         }
 
         // Flatten
-        List<Item> mailableLoot = [.. loot.SelectMany(x => x)];
+        IEnumerable<Item> mailableLoot = [.. loot.SelectMany(x => x)];
 
         // Send message from fence giving player reward generated above
         mailSendService.SendLocalisedNpcMessageToPlayer(