Try to devirtualize ArrayPool.Shared

src/mscorlib/shared/System/Buffers/ArrayPool.cs

@@ -2,8 +2,18 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+using System.Runtime.CompilerServices;
+
 namespace System.Buffers
 {
+    internal static class ArrayPools
+    {
+        private static TlsOverPerCoreLockedStacksArrayPool<byte> s_bytePool = new TlsOverPerCoreLockedStacksArrayPool<byte>();
+        private static TlsOverPerCoreLockedStacksArrayPool<char> s_charPool = new TlsOverPerCoreLockedStacksArrayPool<char>();
+
+        internal static TlsOverPerCoreLockedStacksArrayPool<byte> BytePool => s_bytePool;
+        internal static TlsOverPerCoreLockedStacksArrayPool<char> CharPool => s_charPool;
+    }
     /// <summary>
     /// Provides a resource pool that enables reusing instances of type <see cref="T:T[]"/>. 
     /// </summary>
@@ -19,6 +29,7 @@ namespace System.Buffers
     /// </remarks>
     public abstract class ArrayPool<T>
     {
+        private static ConfigurableArrayPool<T> s_generalPool = typeof(T) == typeof(byte) || typeof(T) == typeof(char) ? null : new ConfigurableArrayPool<T>();
         /// <summary>
         /// Retrieves a shared <see cref="ArrayPool{T}"/> instance.
         /// </summary>
@@ -33,9 +44,25 @@ public abstract class ArrayPool<T>
         /// optimized for very fast access speeds, at the expense of more memory consumption.
         /// The shared pool instance is created lazily on first access.
         /// </remarks>
-        public static ArrayPool<T> Shared { get; } =
-            typeof(T) == typeof(byte) || typeof(T) == typeof(char) ? new TlsOverPerCoreLockedStacksArrayPool<T>() :
-            Create();
+        public static ArrayPool<T> Shared
+        {
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]
+            get
+            {
+                if (typeof(T) == typeof(byte))
+                {
+                    return (ArrayPool<T>)(object)ArrayPools.BytePool;
+                }
+                else if (typeof(T) == typeof(char))
+                {
+                    return (ArrayPool<T>)(object)ArrayPools.CharPool;
+                }
+                else
+                {
+                    return s_generalPool;
+                }
+            }
+        }
 
         /// <summary>
         /// Creates a new <see cref="ArrayPool{T}"/> instance using default configuration options.