diff --git a/Orm/Xtensive.Orm/Tuples/Packed/TupleLayout.cs b/Orm/Xtensive.Orm/Tuples/Packed/TupleLayout.cs
index 153b6c732..685cadeef 100644
--- a/Orm/Xtensive.Orm/Tuples/Packed/TupleLayout.cs
+++ b/Orm/Xtensive.Orm/Tuples/Packed/TupleLayout.cs
@@ -4,7 +4,6 @@
 // Created by: Denis Krjuchkov
 // Created:    2012.12.29
 
-using System;
 using System.Runtime.CompilerServices;
 using Xtensive.Reflection;
 
@@ -53,79 +52,62 @@ internal static class ValueFieldAccessorResolver
       private static readonly ValueFieldAccessor GuidAccessor = new GuidFieldAccessor();
       private static readonly ValueFieldAccessor DateTimeOffsetAccessor = new DateTimeOffsetFieldAccessor();
 
-      private static readonly ObjectFieldAccessor ObjectAccessor = new ObjectFieldAccessor();
+      private static readonly ObjectFieldAccessor ObjectAccessor = new();
 
-      private static readonly int NullableTypeMetadataToken = WellKnownTypes.NullableOfT.MetadataToken;
-
-      public static ValueFieldAccessor GetValue(Type probeType)
+      private sealed class TypeReferenceEqualityComparer : IEqualityComparer<Type>
       {
-        return (probeType.MetadataToken ^ NullableTypeMetadataToken) == 0
-          ? (ResolveByNullableType(probeType) ?? TryResolveNullableEnum(probeType))
-          : (ResolveByType(probeType) ?? TryResolveEnum(probeType));
+        public static readonly TypeReferenceEqualityComparer Instance = new();
+        public bool Equals(Type x, Type y) => ReferenceEquals(x, y);
+        public int GetHashCode(Type obj) => obj.GetHashCode();
       }
 
-      private static ValueFieldAccessor ResolveByType(Type type)
+      private static readonly Dictionary<Type, ValueFieldAccessor> TypeToAccessor = new(TypeReferenceEqualityComparer.Instance)
       {
-        return ReferenceEquals(type, WellKnownTypes.Int64) ? Int64Accessor :
-          ReferenceEquals(type, WellKnownTypes.Guid) ? GuidAccessor :
-          ReferenceEquals(type, WellKnownTypes.Int32) ? Int32Accessor :
-          ReferenceEquals(type, WellKnownTypes.Bool) ? BoolAccessor :
-          ReferenceEquals(type, WellKnownTypes.DateTime) ? DateTimeAccessor :
-          ReferenceEquals(type, WellKnownTypes.TimeSpan) ? TimeSpanAccessor :
-          ReferenceEquals(type, WellKnownTypes.Double) ? DoubleAccessor :
-          ReferenceEquals(type, WellKnownTypes.Decimal) ? DecimalAccessor :
-          ReferenceEquals(type, WellKnownTypes.Single) ? SingleAccessor :
-          ReferenceEquals(type, WellKnownTypes.DateTimeOffset) ? DateTimeOffsetAccessor :
-          ReferenceEquals(type, WellKnownTypes.DateOnly) ? DateOnlyAccessor :
-          ReferenceEquals(type, WellKnownTypes.TimeOnly) ? TimeOnlyAccessor :
-          ReferenceEquals(type, WellKnownTypes.Int16) ? Int16Accessor :
-          ReferenceEquals(type, WellKnownTypes.Byte) ? ByteAccessor :
-          ReferenceEquals(type, WellKnownTypes.SByte) ? SByteAccessor :
-          ReferenceEquals(type, WellKnownTypes.UInt16) ? UInt16Accessor :
-          ReferenceEquals(type, WellKnownTypes.UInt32) ? UInt32Accessor :
-          ReferenceEquals(type, WellKnownTypes.UInt64) ? UInt64Accessor : null;
-      }
+        [WellKnownTypes.Int64] = Int64Accessor,
+        [WellKnownTypes.Guid] = GuidAccessor,
+        [WellKnownTypes.Int32] = Int32Accessor,
+        [WellKnownTypes.Bool] = BoolAccessor,
+        [WellKnownTypes.DateTime] = DateTimeAccessor,
+        [WellKnownTypes.TimeSpan] = TimeSpanAccessor,
+        [WellKnownTypes.Double] = DoubleAccessor,
+        [WellKnownTypes.Decimal] = DecimalAccessor,
+        [WellKnownTypes.Single] = SingleAccessor,
+        [WellKnownTypes.DateTimeOffset] = DateTimeOffsetAccessor,
+        [WellKnownTypes.DateOnly] = DateOnlyAccessor,
+        [WellKnownTypes.TimeOnly] = TimeOnlyAccessor,
+        [WellKnownTypes.Int16] = Int16Accessor,
+        [WellKnownTypes.Byte] = ByteAccessor,
+        [WellKnownTypes.SByte] = SByteAccessor,
+        [WellKnownTypes.UInt16] = UInt16Accessor,
+        [WellKnownTypes.UInt32] = UInt32Accessor,
+        [WellKnownTypes.UInt64] = UInt64Accessor,
+        [WellKnownTypes.NullableBool] = BoolAccessor,
+        [WellKnownTypes.NullableInt32] = Int32Accessor,
+        [WellKnownTypes.NullableDouble] = DoubleAccessor,
+        [WellKnownTypes.NullableDecimal] = DecimalAccessor,
+        [WellKnownTypes.NullableInt64] = Int64Accessor,
+        [WellKnownTypes.NullableDateTime] = DateTimeAccessor,
+        [WellKnownTypes.NullableTimeSpan] = TimeSpanAccessor,
+        [WellKnownTypes.NullableDateTimeOffset] = DateTimeOffsetAccessor,
+        [WellKnownTypes.NullableSingle] = SingleAccessor,
+        [WellKnownTypes.NullableDateOnly] = DateOnlyAccessor,
+        [WellKnownTypes.NullableTimeOnly] = TimeOnlyAccessor,
+        [WellKnownTypes.NullableGuid] = GuidAccessor,
+        [WellKnownTypes.NullableInt16] = Int16Accessor,
+        [WellKnownTypes.NullableByte] = ByteAccessor,
+        [WellKnownTypes.NullableSByte] = SByteAccessor,
+        [WellKnownTypes.NullableUInt16] = UInt16Accessor,
+        [WellKnownTypes.NullableUInt32] = UInt32Accessor,
+        [WellKnownTypes.NullableUInt64] = UInt64Accessor
+      };
 
-      private static ValueFieldAccessor ResolveByNullableType(Type type)
-      {
-        return ReferenceEquals(type, WellKnownTypes.NullableBool) ? BoolAccessor :
-          ReferenceEquals(type, WellKnownTypes.NullableInt32) ? Int32Accessor :
-          ReferenceEquals(type, WellKnownTypes.NullableDouble) ? DoubleAccessor :
-          ReferenceEquals(type, WellKnownTypes.NullableDecimal) ? DecimalAccessor :
-          ReferenceEquals(type, WellKnownTypes.NullableInt64) ? Int64Accessor :
-          ReferenceEquals(type, WellKnownTypes.NullableDateTime) ? DateTimeAccessor :
-          ReferenceEquals(type, WellKnownTypes.NullableTimeSpan) ? TimeSpanAccessor :
-          ReferenceEquals(type, WellKnownTypes.NullableDateTimeOffset) ? DateTimeOffsetAccessor :
-          ReferenceEquals(type, WellKnownTypes.NullableSingle) ? SingleAccessor :
-          ReferenceEquals(type, WellKnownTypes.NullableDateOnly) ? DateOnlyAccessor :
-          ReferenceEquals(type, WellKnownTypes.NullableTimeOnly) ? TimeOnlyAccessor :
-          ReferenceEquals(type, WellKnownTypes.NullableGuid) ? GuidAccessor :
-          ReferenceEquals(type, WellKnownTypes.NullableInt16) ? Int16Accessor :
-          ReferenceEquals(type, WellKnownTypes.NullableByte) ? ByteAccessor :
-          ReferenceEquals(type, WellKnownTypes.NullableSByte) ? SByteAccessor :
-          ReferenceEquals(type, WellKnownTypes.NullableUInt16) ? UInt16Accessor :
-          ReferenceEquals(type, WellKnownTypes.NullableUInt32) ? UInt32Accessor :
-          ReferenceEquals(type, WellKnownTypes.NullableUInt64) ? UInt64Accessor : null;
-      }
-
-      private static ValueFieldAccessor TryResolveEnum(Type type)
-      {
-        if (!type.IsEnum) {
-          return null;
-        }
-        type = Enum.GetUnderlyingType(type);
-        return ResolveByType(type);
-      }
+      private static readonly int NullableTypeMetadataToken = WellKnownTypes.NullableOfT.MetadataToken;
 
-      private static ValueFieldAccessor TryResolveNullableEnum(Type type)
-      {
-        var generic = type.GetGenericArguments()[0];
-        if (!generic.IsEnum) {
-          return null;
-        }
-        type = Enum.GetUnderlyingType(generic);
-        return ResolveByType(type);
-      }
+      public static ValueFieldAccessor GetValue(Type probeType) =>
+        TypeToAccessor.GetValueOrDefault(probeType)
+        ?? ((probeType.MetadataToken == NullableTypeMetadataToken ? probeType.GetGenericArguments()[0] : probeType) is { IsEnum: true } enumType
+          ? TypeToAccessor.GetValueOrDefault(Enum.GetUnderlyingType(enumType))
+          : null);
     }
 
     internal delegate void CounterIncrementer(ref Counters counters);
@@ -134,14 +116,13 @@ private static ValueFieldAccessor TryResolveNullableEnum(Type type)
 
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     public static void ConfigureFieldAccessor(ref PackedFieldDescriptor descriptor, Type fieldType) =>
-      descriptor.AccessorIndex = ((PackedFieldAccessor)ValueFieldAccessorResolver.GetValue(fieldType))?.Index ?? ObjectFieldAccessor.FixedIndex;
+      descriptor.AccessorIndex = ValueFieldAccessorResolver.GetValue(fieldType)?.Index ?? ObjectFieldAccessor.FixedIndex;
 
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     public static void ConfigureLen1(ref Type fieldType, ref PackedFieldDescriptor descriptor, out int valuesLength,
       out int objectsLength)
     {
-      var valueAccessor = ValueFieldAccessorResolver.GetValue(fieldType);
-      if (valueAccessor != null) {
+      if (ValueFieldAccessorResolver.GetValue(fieldType) is { } valueAccessor) {
         descriptor.AccessorIndex = valueAccessor.Index;
         descriptor.DataPosition = Val064BitCount;
 
@@ -264,4 +245,4 @@ private static void ConfigureFieldPhase1(ref PackedFieldDescriptor descriptor, r
       descriptor.Index = counters.ObjectCounter++;
     }
   }
-}
\ No newline at end of file
+}