Update DynamicGetMemberBinder to only add BindingRestrictions for dyn…

…amic type and cache the DynamicMetaObject

System.Linq.Dynamic.Core.sln

@@ -159,6 +159,8 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Microsoft.EntityFrameworkCo
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "System.Linq.Dynamic.Core.Tests.Net8", "test\System.Linq.Dynamic.Core.Tests.Net8\System.Linq.Dynamic.Core.Tests.Net8.csproj", "{CEBE3A33-4814-42A4-BD8E-F7F2308A4C8C}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "ConsoleAppPerformanceTest", "src-console\ConsoleAppPerformanceTest\ConsoleAppPerformanceTest.csproj", "{067C00CF-29FA-4643-814D-3A3C3C84634F}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -1039,6 +1041,22 @@ Global
 		{CEBE3A33-4814-42A4-BD8E-F7F2308A4C8C}.Release|x64.Build.0 = Release|Any CPU
 		{CEBE3A33-4814-42A4-BD8E-F7F2308A4C8C}.Release|x86.ActiveCfg = Release|Any CPU
 		{CEBE3A33-4814-42A4-BD8E-F7F2308A4C8C}.Release|x86.Build.0 = Release|Any CPU
+		{067C00CF-29FA-4643-814D-3A3C3C84634F}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{067C00CF-29FA-4643-814D-3A3C3C84634F}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{067C00CF-29FA-4643-814D-3A3C3C84634F}.Debug|ARM.ActiveCfg = Debug|Any CPU
+		{067C00CF-29FA-4643-814D-3A3C3C84634F}.Debug|ARM.Build.0 = Debug|Any CPU
+		{067C00CF-29FA-4643-814D-3A3C3C84634F}.Debug|x64.ActiveCfg = Debug|Any CPU
+		{067C00CF-29FA-4643-814D-3A3C3C84634F}.Debug|x64.Build.0 = Debug|Any CPU
+		{067C00CF-29FA-4643-814D-3A3C3C84634F}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{067C00CF-29FA-4643-814D-3A3C3C84634F}.Debug|x86.Build.0 = Debug|Any CPU
+		{067C00CF-29FA-4643-814D-3A3C3C84634F}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{067C00CF-29FA-4643-814D-3A3C3C84634F}.Release|Any CPU.Build.0 = Release|Any CPU
+		{067C00CF-29FA-4643-814D-3A3C3C84634F}.Release|ARM.ActiveCfg = Release|Any CPU
+		{067C00CF-29FA-4643-814D-3A3C3C84634F}.Release|ARM.Build.0 = Release|Any CPU
+		{067C00CF-29FA-4643-814D-3A3C3C84634F}.Release|x64.ActiveCfg = Release|Any CPU
+		{067C00CF-29FA-4643-814D-3A3C3C84634F}.Release|x64.Build.0 = Release|Any CPU
+		{067C00CF-29FA-4643-814D-3A3C3C84634F}.Release|x86.ActiveCfg = Release|Any CPU
+		{067C00CF-29FA-4643-814D-3A3C3C84634F}.Release|x86.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -1098,6 +1116,7 @@ Global
 		{7A31366C-DD98-41A3-A0C1-A97068BD9658} = {BCA2A024-9032-4E56-A6C4-17A15D921728}
 		{C774DAE7-54A0-4FCD-A3B7-3CB63D7E112D} = {DBD7D9B6-FCC7-4650-91AF-E6457573A68F}
 		{CEBE3A33-4814-42A4-BD8E-F7F2308A4C8C} = {8463ED7E-69FB-49AE-85CF-0791AFD98E38}
+		{067C00CF-29FA-4643-814D-3A3C3C84634F} = {7971CAEB-B9F2-416B-966D-2D697C4C1E62}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {94C56722-194E-4B8B-BC23-B3F754E89A20}

src-console/ConsoleAppPerformanceTest/ConsoleAppPerformanceTest.csproj

@@ -0,0 +1,15 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+    <PropertyGroup>
+        <OutputType>Exe</OutputType>
+        <TargetFramework>net48</TargetFramework>
+        <ImplicitUsings>enable</ImplicitUsings>
+        <Nullable>enable</Nullable>
+        <LangVersion>12</LangVersion>
+    </PropertyGroup>
+
+    <ItemGroup>
+      <ProjectReference Include="..\..\src\System.Linq.Dynamic.Core\System.Linq.Dynamic.Core.csproj" />
+    </ItemGroup>
+
+</Project>

src-console/ConsoleAppPerformanceTest/Program.cs

@@ -0,0 +1,32 @@
+using System.Linq.Dynamic.Core;
+
+TestDynamic();
+return;
+
+static void TestDynamic()
+{
+    var list = new List<Demo>();
+    for (int i = 0; i < 100000; i++)
+    {
+        list.Add(new Demo { ID = i, Name = $"Name {i}", Description = $"Description {i}" });
+    }
+
+    var xTimeAll = System.Diagnostics.Stopwatch.StartNew();
+    var query = list.AsQueryable().Select(typeof(Demo), "new { ID, Name }").ToDynamicList();
+    Console.WriteLine($"Total 1st Query: {(int)xTimeAll.Elapsed.TotalMilliseconds}ms");
+
+    xTimeAll.Restart();
+    _ = query.AsQueryable().Select("ID").Cast<int>().ToList();
+    Console.WriteLine($"Total nd Query: {(int)xTimeAll.Elapsed.TotalMilliseconds}ms");
+
+    xTimeAll.Restart();
+    _ = query.AsQueryable().Select("new { it.ID as Idee } ").ToDynamicList();
+    Console.WriteLine($"Total 3rd Query: {(int)xTimeAll.Elapsed.TotalMilliseconds}ms");
+}
+
+class Demo
+{
+    public int ID { get; set; }
+    public string Name { get; set; }
+    public string Description { get; set; }
+}

src/System.Linq.Dynamic.Core/DynamicGetMemberBinder.cs

@@ -1,5 +1,6 @@
 #if !NET35 && !UAP10_0 && !NETSTANDARD1_3
 using System.Collections;
+using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.Dynamic;
 using System.Linq.Expressions;
@@ -14,6 +15,7 @@ namespace System.Linq.Dynamic.Core;
 internal class DynamicGetMemberBinder : GetMemberBinder
 {
     private static readonly MethodInfo DynamicGetMemberMethod = typeof(DynamicGetMemberBinder).GetMethod(nameof(GetDynamicMember))!;
+    private readonly ConcurrentDictionary<Tuple<Type, string, bool>, DynamicMetaObject> _metaObjectCache = new();
 
     public DynamicGetMemberBinder(string name, ParsingConfig? config) : base(name, config?.IsCaseSensitive != true)
     {
@@ -28,8 +30,20 @@ public override DynamicMetaObject FallbackGetMember(DynamicMetaObject target, Dy
             Expression.Constant(IgnoreCase));
 
         // Fix #907 and #912: "The result of the dynamic binding produced by the object with type '<>f__AnonymousType1`4' for the binder 'System.Linq.Dynamic.Core.DynamicGetMemberBinder' needs at least one restriction.".
-        var restrictions = BindingRestrictions.GetInstanceRestriction(target.Expression, target.Value);
-        return new DynamicMetaObject(methodCallExpression, restrictions, target.Value!);
+        // Fix #921: "Slow Performance"
+        // Only add TypeRestriction if it's a Dynamic type and make sure to cache the DynamicMetaObject.
+        if (target.Value is IDynamicMetaObjectProvider)
+        {
+            var key = new Tuple<Type, string, bool>(target.LimitType, Name, IgnoreCase);
+
+            return _metaObjectCache.GetOrAdd(key, _ =>
+            {
+                var restrictions = BindingRestrictions.GetTypeRestriction(target.Expression, target.LimitType);
+                return new DynamicMetaObject(methodCallExpression, restrictions, target.Value);
+            });
+        }
+
+        return DynamicMetaObject.Create(target.Value!, methodCallExpression);
     }
 
     public static object? GetDynamicMember(object value, string name, bool ignoreCase)