diff --git a/Directory.Build.props b/Directory.Build.props
index 5068e67a..ffbcc1df 100644
--- a/Directory.Build.props
+++ b/Directory.Build.props
@@ -14,6 +14,11 @@
     <DefineConstants Condition="$(UseBitArray) == 'true'">$(DefineConstants);USE_BITARRAY</DefineConstants>
   </PropertyGroup>
 
+  <PropertyGroup>
+    <UseArray Condition="'$(UseArray)' == ''">$(UseDefines)</UseArray>
+    <DefineConstants Condition="$(UseArray) == 'true'">$(DefineConstants);USE_ARRAY</DefineConstants>
+  </PropertyGroup>
+
   <PropertyGroup>
     <LocationAsStruct Condition="'$(LocationAsStruct)' == ''">$(UseDefines)</LocationAsStruct>
     <DefineConstants Condition="$(LocationAsStruct) == 'true'">$(DefineConstants);LOCATION_AS_STRUCT</DefineConstants>
diff --git a/src/FactorioTools/CollectionExtensions.cs b/src/FactorioTools/CollectionExtensions.cs
index 5523321e..7c3eeaf0 100644
--- a/src/FactorioTools/CollectionExtensions.cs
+++ b/src/FactorioTools/CollectionExtensions.cs
@@ -27,10 +27,10 @@ public static ILocationDictionary<TValue> ToDictionary<TItem, TValue>(
         return dictionary;
     }
 
-    public static List<Location> Distinct(this IReadOnlyCollection<Location> locations, Context context)
+    public static IItemList<Location> Distinct(this IReadOnlyCollection<Location> locations, Context context)
     {
         var set = context.GetLocationSet(locations.Count);
-        var output = new List<Location>(locations.Count);
+        var output = Collection.List<Location>(locations.Count);
         foreach (var location in locations)
         {
             if (set.Add(location))
@@ -57,9 +57,9 @@ public static ILocationSet ToReadOnlySet(this IReadOnlyCollection<Location> loca
     }
 
 #if ENABLE_VISUALIZER
-    public static List<DelaunatorSharp.IPoint> ToDelaunatorPoints(this ILocationSet set)
+    public static IItemList<DelaunatorSharp.IPoint> ToDelaunatorPoints(this ILocationSet set)
     {
-        var points = new List<DelaunatorSharp.IPoint>();
+        var points = Collection.List<DelaunatorSharp.IPoint>();
         foreach (var item in set.EnumerateItems())
         {
             points.Add(new DelaunatorSharp.Point(item.X, item.Y));
@@ -68,9 +68,9 @@ public static ILocationSet ToReadOnlySet(this IReadOnlyCollection<Location> loca
         return points;
     }
 
-    public static List<DelaunatorSharp.IPoint> ToDelaunatorPoints<T>(this ILocationDictionary<T> dictionary)
+    public static IItemList<DelaunatorSharp.IPoint> ToDelaunatorPoints<T>(this ILocationDictionary<T> dictionary)
     {
-        var points = new List<DelaunatorSharp.IPoint>();
+        var points = Collection.List<DelaunatorSharp.IPoint>();
         foreach (var item in dictionary.Keys)
         {
             points.Add(new DelaunatorSharp.Point(item.X, item.Y));
@@ -186,9 +186,9 @@ public static ILocationSet ToReadOnlySet(this IReadOnlyCollection<Location> loca
         return min;
     }
 
-    public static List<TSource> ToList<TSource>(this IReadOnlyCollection<TSource> source)
+    public static IItemList<TSource> ToList<TSource>(this IReadOnlyCollection<TSource> source)
     {
-        var output = new List<TSource>(source.Count);
+        var output = Collection.List<TSource>(source.Count);
         output.AddRange(source);
         return output;
     }
diff --git a/src/FactorioTools/OilField/Containers/DictionaryList.cs b/src/FactorioTools/OilField/Containers/DictionaryList.cs
new file mode 100644
index 00000000..bba42c53
--- /dev/null
+++ b/src/FactorioTools/OilField/Containers/DictionaryList.cs
@@ -0,0 +1,126 @@
+using System;
+using System.Collections;
+using System.Collections.Generic;
+
+namespace Knapcode.FactorioTools.OilField;
+
+public static class Collection
+{
+    public static IItemList<T> List<T>()
+    {
+#if USE_ARRAY
+        return new StandardList<T>();
+#else
+        return new DictionaryList<T>();
+#endif
+    }
+
+    public static IItemList<T> List<T>(int capacity)
+    {
+#if USE_ARRAY
+        return new StandardList<T>(capacity);
+#else
+        return new DictionaryList<T>(capacity);
+#endif
+    }
+}
+
+public interface IItemList<T>
+{
+    T this[int index] { get; set; }
+    int Count { get; }
+
+    void Add(T item);
+    void AddRange(IReadOnlyCollection<T> collection);
+    void Sort(Comparer<T> comparer);
+}
+
+public class StandardList<T> : IItemList<T>
+{
+    private readonly List<T> _list;
+
+    public StandardList()
+    {
+        _list = new List<T>();
+    }
+
+    public StandardList(int capacity)
+    {
+        _list = new List<T>(capacity);
+    }
+
+    public T this[int index]
+    {
+        get => _list[index];
+        set => _list[index] = value;
+    }
+
+    public int Count => _list.Count;
+
+    public void Add(T item)
+    {
+        _list.Add(item);
+    }
+
+    public void AddRange(IReadOnlyCollection<T> collection)
+    {
+        _list.AddRange(collection);
+    }
+
+    public void Sort(Comparer<T> comparer)
+    {
+        _list.Sort(comparer);
+    }
+}
+
+public class DictionaryList<T> : IItemList<T>
+{
+    private readonly Dictionary<int, T> _dictionary;
+
+    public DictionaryList()
+    {
+        _dictionary = new Dictionary<int, T>();
+    }
+
+    public DictionaryList(int capacity)
+    {
+        _dictionary = new Dictionary<int, T>(capacity);
+    }
+
+    public T this[int index]
+    {
+        get
+        {
+            if (index >= _dictionary.Count)
+            {
+                throw new IndexOutOfRangeException();
+            }
+
+            return _dictionary[index];
+        }
+        set
+        {
+            if (index >= _dictionary.Count)
+            {
+                throw new IndexOutOfRangeException();
+            }
+
+            _dictionary[index] = value;
+        }
+    }
+
+    public int Count => _dictionary.Count;
+
+    public void Add(T item)
+    {
+        _dictionary.Add(_dictionary.Count, item);
+    }
+
+    public void AddRange(IReadOnlyCollection<T> collection)
+    {
+        foreach (var item in collection)
+        {
+            _dictionary.Add(_dictionary.Count, item);
+        }
+    }
+}
diff --git a/src/FactorioTools/OilField/Helpers.cs b/src/FactorioTools/OilField/Helpers.cs
index fddb8d2a..ffa283d0 100644
--- a/src/FactorioTools/OilField/Helpers.cs
+++ b/src/FactorioTools/OilField/Helpers.cs
@@ -72,14 +72,14 @@ public static void PopulateCenterToTerminals(ILocationDictionary<List<TerminalLo
         }
     }
 
-    public static ILocationDictionary<List<TerminalLocation>> GetLocationToTerminals(Context context, ILocationDictionary<List<TerminalLocation>> centerToTerminals)
+    public static ILocationDictionary<IItemList<TerminalLocation>> GetLocationToTerminals(Context context, ILocationDictionary<List<TerminalLocation>> centerToTerminals)
     {
-        var locationToTerminals = context.GetLocationDictionary<List<TerminalLocation>>();
+        var locationToTerminals = context.GetLocationDictionary<IItemList<TerminalLocation>>();
         PopulateLocationToTerminals(locationToTerminals, centerToTerminals);
         return locationToTerminals;
     }
 
-    public static void PopulateLocationToTerminals(ILocationDictionary<List<TerminalLocation>> locationToTerminals, ILocationDictionary<List<TerminalLocation>> centerToTerminals)
+    public static void PopulateLocationToTerminals(ILocationDictionary<IItemList<TerminalLocation>> locationToTerminals, ILocationDictionary<List<TerminalLocation>> centerToTerminals)
     {
         foreach (var terminals in centerToTerminals.Values)
         {
@@ -87,7 +87,7 @@ public static void PopulateLocationToTerminals(ILocationDictionary<List<Terminal
             {
                 if (!locationToTerminals.TryGetValue(terminal.Terminal, out var list))
                 {
-                    list = new List<TerminalLocation>(2);
+                    list = Collection.List<TerminalLocation>(2);
                     locationToTerminals.Add(terminal.Terminal, list);
                 }
 
@@ -98,7 +98,7 @@ public static void PopulateLocationToTerminals(ILocationDictionary<List<Terminal
 
     public static (ILocationDictionary<TInfo> CandidateToInfo, CountedBitArray CoveredEntities, ILocationDictionary<BeaconCenter> Providers) GetBeaconCandidateToCovered<TInfo>(
         Context context,
-        List<ProviderRecipient> recipients,
+        IItemList<ProviderRecipient> recipients,
         ICandidateFactory<TInfo> candidateFactory,
         bool removeUnused)
         where TInfo : CandidateInfo
@@ -118,7 +118,7 @@ public static (ILocationDictionary<TInfo> CandidateToInfo, CountedBitArray Cover
 
     public static (ILocationDictionary<TInfo> CandidateToInfo, CountedBitArray CoveredEntities, ILocationDictionary<ElectricPoleCenter> Providers) GetElectricPoleCandidateToCovered<TInfo>(
         Context context,
-        List<ProviderRecipient> recipients,
+        IItemList<ProviderRecipient> recipients,
         ICandidateFactory<TInfo> candidateFactory,
         bool removeUnused)
         where TInfo : CandidateInfo
@@ -138,7 +138,7 @@ public static (ILocationDictionary<TInfo> CandidateToInfo, CountedBitArray Cover
 
     private static (ILocationDictionary<TInfo> CandidateToInfo, CountedBitArray CoveredEntities, ILocationDictionary<TProvider> Providers) GetCandidateToCovered<TProvider, TInfo>(
         Context context,
-        List<ProviderRecipient> recipients,
+        IItemList<ProviderRecipient> recipients,
         ICandidateFactory<TInfo> candidateFactory,
         int providerWidth,
         int providerHeight,
@@ -443,7 +443,7 @@ public static bool DoesProviderFit(
         return true;
     }
 
-    public static double GetEntityDistance(List<ProviderRecipient> poweredEntities, Location candidate, CountedBitArray covered)
+    public static double GetEntityDistance(IItemList<ProviderRecipient> poweredEntities, Location candidate, CountedBitArray covered)
     {
         double sum = 0;
         for (var i = 0; i < poweredEntities.Count; i++)
@@ -1119,7 +1119,7 @@ public static List<Location> MakeStraightLine(Location a, Location b)
         throw new ArgumentException("The two points must be one the same line either horizontally or vertically.");
     }
 
-    public static List<Endpoints> PointsToLines(IReadOnlyCollection<Location> nodes)
+    public static IItemList<Endpoints> PointsToLines(IReadOnlyCollection<Location> nodes)
     {
         return PointsToLines(nodes.ToList(), sort: true);
     }
@@ -1127,7 +1127,7 @@ public static List<Endpoints> PointsToLines(IReadOnlyCollection<Location> nodes)
     /// <summary>
     /// Source: https://github.com/teoxoy/factorio-blueprint-editor/blob/21ab873d8316a41b9a05c719697d461d3ede095d/packages/editor/src/core/generators/util.ts#L62
     /// </summary>
-    public static List<Endpoints> PointsToLines(IReadOnlyList<Location> nodes, bool sort)
+    public static IItemList<Endpoints> PointsToLines(IReadOnlyList<Location> nodes, bool sort)
     {
         IReadOnlyList<Location> filteredNodes;
         if (sort)
diff --git a/src/FactorioTools/OilField/Steps/AddElectricPoles.cs b/src/FactorioTools/OilField/Steps/AddElectricPoles.cs
index b5149098..58b8d5e0 100644
--- a/src/FactorioTools/OilField/Steps/AddElectricPoles.cs
+++ b/src/FactorioTools/OilField/Steps/AddElectricPoles.cs
@@ -312,9 +312,9 @@ public ElectricPoleCandidateInfo Create(CountedBitArray covered)
         }
     }
     
-    private static (List<Location>? ElectricPoleList, CountedBitArray CoveredEntities) AddElectricPolesAroundEntities(
+    private static (IItemList<Location>? ElectricPoleList, CountedBitArray CoveredEntities) AddElectricPolesAroundEntities(
         Context context,
-        List<ProviderRecipient> poweredEntities,
+        IItemList<ProviderRecipient> poweredEntities,
         CountedBitArray? entitiesToPowerFirst)
     {
         (var allCandidateToInfo, var coveredEntities, var electricPoles2) = GetElectricPoleCandidateToCovered(
@@ -472,8 +472,8 @@ private static void PopulateCandidateToInfo(
         Context context,
         ILocationDictionary<ElectricPoleCandidateInfo> candidateToInfo,
         CountedBitArray? entitiesToPowerFirst,
-        List<ProviderRecipient> poweredEntities,
-        List<Location> electricPoleList)
+        IItemList<ProviderRecipient> poweredEntities,
+        IItemList<Location> electricPoleList)
     {
         foreach ((var candidate, var info) in candidateToInfo.EnumeratePairs())
         {