feat: network writer pool to avoid expensive allocations

Assets/Mirror/Runtime/NetworkWriterPool.cs

@@ -0,0 +1,28 @@
+using System.Collections.Generic;
+
+namespace Mirror
+{
+
+    public static class NetworkWriterPool
+    {
+        static readonly Stack<NetworkWriter> pool = new Stack<NetworkWriter>();
+
+        public static NetworkWriter GetWriter()
+        {
+            if (pool.Count != 0)
+            {
+                NetworkWriter writer = pool.Pop();
+                // reset cached writer length and position
+                writer.SetLength(0);
+                return writer;
+            }
+
+            return new NetworkWriter();
+        }
+
+        public static void Recycle(NetworkWriter writer)
+        {
+            pool.Push(writer);
+        }
+    }
+}