diff --git a/shadowsocks-csharp/Encryption/Stream/StreamTableNativeEncryptor.cs b/shadowsocks-csharp/Encryption/Stream/StreamTableNativeEncryptor.cs
index 7f1a6494..697e0b17 100644
--- a/shadowsocks-csharp/Encryption/Stream/StreamTableNativeEncryptor.cs
+++ b/shadowsocks-csharp/Encryption/Stream/StreamTableNativeEncryptor.cs
@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Runtime.CompilerServices;
 using System.Text;
 using System.Threading.Tasks;
 
@@ -25,11 +26,13 @@ namespace Shadowsocks.Encryption.Stream
             {
                 _encryptTable[i] = (byte)i;
             }
+            Span<byte> t = _encryptTable;
             // copy array 1024 times? excuse me?
             for (int i = 1; i < 1024; i++)
             {
-                _encryptTable = MergeSort(_encryptTable, a, i);
+                t = MergeSort(t, a, i);
             }
+            _encryptTable = t.ToArray();
             for (int i = 0; i < 256; i++)
             {
                 _decryptTable[_encryptTable[i]] = (byte)i;
@@ -103,37 +106,32 @@ namespace Shadowsocks.Encryption.Stream
         #region Table
         private byte[] _encryptTable = new byte[256];
         private byte[] _decryptTable = new byte[256];
+        private byte[] _tmp = new byte[256];
 
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
         private static long Compare(byte x, byte y, ulong a, int i)
         {
             return (long)(a % (ulong)(x + i)) - (long)(a % (ulong)(y + i));
         }
 
-        private byte[] MergeSort(byte[] array, ulong a, int j)
+        byte[] buf = new byte[1024];
+        private Span<byte> MergeSort(Span<byte> array, ulong a, int j)
         {
             if (array.Length == 1)
             {
                 return array;
             }
             int middle = array.Length / 2;
-            byte[] left = new byte[middle];
-            for (int i = 0; i < middle; i++)
-            {
-                left[i] = array[i];
-            }
-            byte[] right = new byte[array.Length - middle];
-            for (int i = 0; i < array.Length - middle; i++)
-            {
-                right[i] = array[i + middle];
-            }
-            left = MergeSort(left, a, j);
-            right = MergeSort(right, a, j);
+
+            Span<byte> left = MergeSort(array.Slice(0, middle), a, j);;
+            Span<byte> right = MergeSort(array.Slice(middle), a, j);
 
             int leftptr = 0;
             int rightptr = 0;
 
             // why a new array?
-            byte[] sorted = new byte[array.Length];
+            Span<byte> sorted = new byte[array.Length];// buf.AsSpan().Slice(0,array.Length); // // _tmp;
+                        
             for (int k = 0; k < array.Length; k++)
             {
                 if (rightptr == right.Length || ((leftptr < left.Length) && (Compare(left[leftptr], right[rightptr], a, j) <= 0)))
diff --git a/shadowsocks-csharp/shadowsocks-csharp.csproj b/shadowsocks-csharp/shadowsocks-csharp.csproj
index 7387b4d0..700ed4f9 100644
--- a/shadowsocks-csharp/shadowsocks-csharp.csproj
+++ b/shadowsocks-csharp/shadowsocks-csharp.csproj
@@ -12,7 +12,7 @@
     <AssemblyName>Shadowsocks</AssemblyName>
     <ApplicationIcon>shadowsocks.ico</ApplicationIcon>
     <StartupObject>Shadowsocks.Program</StartupObject>
-    <Nullable>enable</Nullable>
+    <Nullable>disable</Nullable>
   </PropertyGroup>
 
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release|AnyCPU'">
diff --git a/shadowsocks-windows.sln b/shadowsocks-windows.sln
index 8ca60bd7..65f53fa7 100644
--- a/shadowsocks-windows.sln
+++ b/shadowsocks-windows.sln
@@ -26,27 +26,17 @@ EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
-		Debug|x86 = Debug|x86
 		Release|Any CPU = Release|Any CPU
-		Release|x86 = Release|x86
 	EndGlobalSection
 	GlobalSection(ProjectConfigurationPlatforms) = postSolution
 		{8C02D2F7-7CDB-4D55-9F25-CD03EF4AA062}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
 		{8C02D2F7-7CDB-4D55-9F25-CD03EF4AA062}.Debug|Any CPU.Build.0 = Debug|Any CPU
-		{8C02D2F7-7CDB-4D55-9F25-CD03EF4AA062}.Debug|x86.ActiveCfg = Debug|Any CPU
-		{8C02D2F7-7CDB-4D55-9F25-CD03EF4AA062}.Debug|x86.Build.0 = Debug|Any CPU
 		{8C02D2F7-7CDB-4D55-9F25-CD03EF4AA062}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{8C02D2F7-7CDB-4D55-9F25-CD03EF4AA062}.Release|Any CPU.Build.0 = Release|Any CPU
-		{8C02D2F7-7CDB-4D55-9F25-CD03EF4AA062}.Release|x86.ActiveCfg = Release|Any CPU
-		{8C02D2F7-7CDB-4D55-9F25-CD03EF4AA062}.Release|x86.Build.0 = Release|Any CPU
 		{45913187-0685-4903-B250-DCEF0479CD86}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
 		{45913187-0685-4903-B250-DCEF0479CD86}.Debug|Any CPU.Build.0 = Debug|Any CPU
-		{45913187-0685-4903-B250-DCEF0479CD86}.Debug|x86.ActiveCfg = Debug|Any CPU
-		{45913187-0685-4903-B250-DCEF0479CD86}.Debug|x86.Build.0 = Debug|Any CPU
 		{45913187-0685-4903-B250-DCEF0479CD86}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{45913187-0685-4903-B250-DCEF0479CD86}.Release|Any CPU.Build.0 = Release|Any CPU
-		{45913187-0685-4903-B250-DCEF0479CD86}.Release|x86.ActiveCfg = Release|Any CPU
-		{45913187-0685-4903-B250-DCEF0479CD86}.Release|x86.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
diff --git a/test/CryptographyTest.cs b/test/CryptographyTest.cs
index 599023d4..bfd2abda 100644
--- a/test/CryptographyTest.cs
+++ b/test/CryptographyTest.cs
@@ -155,10 +155,7 @@ namespace Shadowsocks.Test
         [TestMethod]
         public void TestNativeTableEncryption()
         {
-            // Too slow, run once to save CPU
-            var enc = new StreamTableNativeEncryptor("table", "barfoo!");
-            var dec = new StreamTableNativeEncryptor("table", "barfoo!");
-            RunEncryptionRound(enc, dec);
+            TestEncryptionMethod(typeof(StreamTableNativeEncryptor), "table");
         }
         [TestMethod]
         public void TestStreamAesBouncyCastleEncryption()