diff --git a/CHANGELOG.md b/CHANGELOG.md
index 17c1780ee..1658a6f95 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,7 +8,8 @@ This document follows the conventions laid out in [Keep a CHANGELOG][].
 ## [unreleased][]
 
 ### Added
-
+-   Improved performance. String marshaling between python and clr now cached. 
+    Cache reduces GC pressure and saves from extensive memory copying.
 -   Added support for embedding python into dotnet core 2.0 (NetStandard 2.0)
 -   Added new build system (pythonnet.15.sln) based on dotnetcore-sdk/xplat(crossplatform msbuild).
     Currently there two side-by-side build systems that produces the same output (net40) from the same sources.
diff --git a/src/embed_tests/Python.EmbeddingTest.csproj b/src/embed_tests/Python.EmbeddingTest.csproj
index 6aa48becc..caffa7256 100644
--- a/src/embed_tests/Python.EmbeddingTest.csproj
+++ b/src/embed_tests/Python.EmbeddingTest.csproj
@@ -104,6 +104,7 @@
     <Compile Include="TestPyWith.cs" />
     <Compile Include="TestRuntime.cs" />
     <Compile Include="TestPyScope.cs" />
+    <Compile Include="TestsSuite.cs" />
     <Compile Include="TestTypeManager.cs" />
     <Compile Include="GlobalTestsSetup.cs" />
   </ItemGroup>
diff --git a/src/embed_tests/TestPythonEngineProperties.cs b/src/embed_tests/TestPythonEngineProperties.cs
index 243349b82..d95942577 100644
--- a/src/embed_tests/TestPythonEngineProperties.cs
+++ b/src/embed_tests/TestPythonEngineProperties.cs
@@ -1,4 +1,5 @@
 using System;
+using System.Diagnostics;
 using NUnit.Framework;
 using Python.Runtime;
 
diff --git a/src/embed_tests/TestRuntime.cs b/src/embed_tests/TestRuntime.cs
index ac1fa1ac0..aeef28135 100644
--- a/src/embed_tests/TestRuntime.cs
+++ b/src/embed_tests/TestRuntime.cs
@@ -34,7 +34,7 @@ public static void PlatformCache()
 
             // Don't shut down the runtime: if the python engine was initialized
             // but not shut down by another test, we'd end up in a bad state.
-	}
+	      }
 
         [Test]
         public static void Py_IsInitializedValue()
diff --git a/src/embed_tests/TestsSuite.cs b/src/embed_tests/TestsSuite.cs
new file mode 100644
index 000000000..44ce2d4b8
--- /dev/null
+++ b/src/embed_tests/TestsSuite.cs
@@ -0,0 +1,18 @@
+using NUnit.Framework;
+using Python.Runtime;
+
+namespace Python.EmbeddingTest
+{
+    [SetUpFixture]
+    public class TestsSuite
+    {
+        [OneTimeTearDown]
+        public void FinalCleanup()
+        {
+            if (PythonEngine.IsInitialized)
+            {
+                PythonEngine.Shutdown();
+            }
+        }
+    }
+}
diff --git a/src/runtime/CustomMarshaler.cs b/src/runtime/CustomMarshaler.cs
index b51911816..507710f87 100644
--- a/src/runtime/CustomMarshaler.cs
+++ b/src/runtime/CustomMarshaler.cs
@@ -18,7 +18,7 @@ public object MarshalNativeToManaged(IntPtr pNativeData)
 
         public abstract IntPtr MarshalManagedToNative(object managedObj);
 
-        public void CleanUpNativeData(IntPtr pNativeData)
+        public virtual void CleanUpNativeData(IntPtr pNativeData)
         {
             Marshal.FreeHGlobal(pNativeData);
         }
@@ -44,7 +44,12 @@ internal class UcsMarshaler : MarshalerBase
         private static readonly MarshalerBase Instance = new UcsMarshaler();
         private static readonly Encoding PyEncoding = Runtime.PyEncoding;
 
-        public override IntPtr MarshalManagedToNative(object managedObj)
+        private const int MaxStringLength = 100;
+        private const int MaxItemSize = 4 * (MaxStringLength + 1);
+        private static readonly EncodedStringsFifoDictionary EncodedStringsDictionary =
+            new EncodedStringsFifoDictionary(10000, MaxItemSize);
+
+        public override unsafe IntPtr MarshalManagedToNative(object managedObj)
         {
             var s = managedObj as string;
 
@@ -53,16 +58,36 @@ public override IntPtr MarshalManagedToNative(object managedObj)
                 return IntPtr.Zero;
             }
 
-            byte[] bStr = PyEncoding.GetBytes(s + "\0");
-            IntPtr mem = Marshal.AllocHGlobal(bStr.Length);
-            try
+            IntPtr mem;
+            int stringBytesCount;
+            if (s.Length <= MaxStringLength)
             {
-                Marshal.Copy(bStr, 0, mem, bStr.Length);
+                if (EncodedStringsDictionary.TryGetValue(s, out mem))
+                {
+                    return mem;
+                }
+
+                stringBytesCount = PyEncoding.GetByteCount(s);
+                mem = EncodedStringsDictionary.AddUnsafe(s);
             }
-            catch (Exception)
+            else
             {
-                Marshal.FreeHGlobal(mem);
-                throw;
+                stringBytesCount = PyEncoding.GetByteCount(s);
+                mem = Marshal.AllocHGlobal(stringBytesCount + 4);
+            }
+
+            fixed (char* str = s)
+            {
+                try
+                {
+                    PyEncoding.GetBytes(str, s.Length, (byte*)mem, stringBytesCount);
+                }
+                catch
+                {
+                    // Do nothing with this. Very strange problem.
+                }
+
+                *(int*)(mem + stringBytesCount) = 0;
             }
 
             return mem;
@@ -106,6 +131,14 @@ public static int GetUnicodeByteLength(IntPtr p)
             }
         }
 
+        public override void CleanUpNativeData(IntPtr pNativeData)
+        {
+            if (!EncodedStringsDictionary.IsKnownPtr(pNativeData))
+            {
+                base.CleanUpNativeData(pNativeData);
+            }
+        }
+
         /// <summary>
         /// Utility function for Marshaling Unicode on PY3 and AnsiStr on PY2.
         /// Use on functions whose Input signatures changed between PY2/PY3.
@@ -118,11 +151,29 @@ public static int GetUnicodeByteLength(IntPtr p)
         /// <remarks>
         /// You MUST deallocate the IntPtr of the Return when done with it.
         /// </remarks>
-        public static IntPtr Py3UnicodePy2StringtoPtr(string s)
+        public unsafe static IntPtr Py3UnicodePy2StringtoPtr(string s)
         {
-            return Runtime.IsPython3
-                ? Instance.MarshalManagedToNative(s)
-                : Marshal.StringToHGlobalAnsi(s);
+            if (Runtime.IsPython3)
+            {
+                int stringBytesCount = PyEncoding.GetByteCount(s);
+                IntPtr mem = Marshal.AllocHGlobal(stringBytesCount + 4);
+                fixed (char* str = s)
+                {
+                    try
+                    {
+                        PyEncoding.GetBytes(str, s.Length, (byte*)mem, stringBytesCount);
+                    }
+                    catch
+                    {
+                        // Do nothing with this. Very strange problem.
+                    }
+
+                    *(int*)(mem + stringBytesCount) = 0;
+                }
+                return mem;
+            }
+
+            return Marshal.StringToHGlobalAnsi(s);
         }
 
         /// <summary>
@@ -208,7 +259,12 @@ internal class Utf8Marshaler : MarshalerBase
         private static readonly MarshalerBase Instance = new Utf8Marshaler();
         private static readonly Encoding PyEncoding = Encoding.UTF8;
 
-        public override IntPtr MarshalManagedToNative(object managedObj)
+        private const int MaxStringLength = 100;
+
+        private static readonly EncodedStringsFifoDictionary EncodedStringsDictionary =
+            new EncodedStringsFifoDictionary(10000, 4 * (MaxStringLength + 1));
+
+        public override unsafe IntPtr MarshalManagedToNative(object managedObj)
         {
             var s = managedObj as string;
 
@@ -217,21 +273,49 @@ public override IntPtr MarshalManagedToNative(object managedObj)
                 return IntPtr.Zero;
             }
 
-            byte[] bStr = PyEncoding.GetBytes(s + "\0");
-            IntPtr mem = Marshal.AllocHGlobal(bStr.Length);
-            try
+            IntPtr mem;
+            int stringBytesCount;
+            if (s.Length <= MaxStringLength)
             {
-                Marshal.Copy(bStr, 0, mem, bStr.Length);
+                if (EncodedStringsDictionary.TryGetValue(s, out mem))
+                {
+                    return mem;
+                }
+
+                stringBytesCount = PyEncoding.GetByteCount(s);
+                mem = EncodedStringsDictionary.AddUnsafe(s);
             }
-            catch (Exception)
+            else
             {
-                Marshal.FreeHGlobal(mem);
-                throw;
+                stringBytesCount = PyEncoding.GetByteCount(s);
+                mem = Marshal.AllocHGlobal(stringBytesCount + 1);
+            }
+
+            fixed (char* str = s)
+            {
+                try
+                {
+                    PyEncoding.GetBytes(str, s.Length, (byte*)mem, stringBytesCount);
+                }
+                catch
+                {
+                    // Do nothing with this. Very strange problem.
+                }
+
+                ((byte*)mem)[stringBytesCount] = 0;
             }
 
             return mem;
         }
 
+        public override void CleanUpNativeData(IntPtr pNativeData)
+        {
+            if (!EncodedStringsDictionary.IsKnownPtr(pNativeData))
+            {
+                base.CleanUpNativeData(pNativeData);
+            }
+        }
+
         public static ICustomMarshaler GetInstance(string cookie)
         {
             return Instance;
diff --git a/src/runtime/Python.Runtime.csproj b/src/runtime/Python.Runtime.csproj
index fc155ca91..00a290988 100644
--- a/src/runtime/Python.Runtime.csproj
+++ b/src/runtime/Python.Runtime.csproj
@@ -76,6 +76,12 @@
     <Reference Include="System" />
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="perf_utils\EncodedStringsFifoDictionary.cs" />
+    <Compile Include="perf_utils\EncodingGetStringPolyfill.cs" />
+    <Compile Include="perf_utils\FifoDictionary.cs" />
+    <Compile Include="perf_utils\RawImmutableMemBlock.cs" />
+    <Compile Include="perf_utils\RawMemoryFifoDictionary.cs" />
+    <Compile Include="perf_utils\RawMemUtils.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
     <Compile Include="..\SharedAssemblyInfo.cs">
       <Link>Properties\SharedAssemblyInfo.cs</Link>
diff --git a/src/runtime/assemblymanager.cs b/src/runtime/assemblymanager.cs
index 3085bb639..039d44951 100644
--- a/src/runtime/assemblymanager.cs
+++ b/src/runtime/assemblymanager.cs
@@ -27,6 +27,7 @@ internal class AssemblyManager
         //    So for multidomain support it is better to have the dict. recreated for each app-domain initialization
         private static ConcurrentDictionary<string, ConcurrentDictionary<Assembly, string>> namespaces =
             new ConcurrentDictionary<string, ConcurrentDictionary<Assembly, string>>();
+
         //private static Dictionary<string, Dictionary<string, string>> generics;
         private static AssemblyLoadEventHandler lhandler;
         private static ResolveEventHandler rhandler;
diff --git a/src/runtime/perf_utils/EncodedStringsFifoDictionary.cs b/src/runtime/perf_utils/EncodedStringsFifoDictionary.cs
new file mode 100644
index 000000000..74a88f0ec
--- /dev/null
+++ b/src/runtime/perf_utils/EncodedStringsFifoDictionary.cs
@@ -0,0 +1,73 @@
+using System;
+
+namespace Python.Runtime
+{
+    using System.Runtime.InteropServices;
+
+    public class EncodedStringsFifoDictionary: IDisposable
+    {
+        private readonly FifoDictionary<string, IntPtr> _innerDictionary;
+
+        private readonly IntPtr _rawMemory;
+
+        private readonly int _allocatedSize;
+
+        public EncodedStringsFifoDictionary(int capacity, int maxItemSize)
+        {
+            if (maxItemSize < 1)
+            {
+                throw new ArgumentOutOfRangeException(
+                    nameof(maxItemSize),
+                    "Maximum item size should be non-zero positive.");
+            }
+
+            _innerDictionary = new FifoDictionary<string, IntPtr>(capacity);
+            _allocatedSize = maxItemSize * capacity;
+            _rawMemory = Marshal.AllocHGlobal(_allocatedSize);
+
+            MaxItemSize = maxItemSize;
+        }
+
+        public int MaxItemSize { get; }
+
+        public bool TryGetValue(string key, out IntPtr value)
+        {
+            return _innerDictionary.TryGetValue(key, out value);
+        }
+
+        public IntPtr AddUnsafe(string key)
+        {
+            int nextSlot = _innerDictionary.NextSlotToAdd;
+            IntPtr ptr = _rawMemory + (MaxItemSize * nextSlot);
+            _innerDictionary.AddUnsafe(key, ptr);
+            return ptr;
+        }
+
+        public bool IsKnownPtr(IntPtr ptr)
+        {
+            var uptr = (ulong)ptr;
+            var umem = (ulong)_rawMemory;
+
+            return uptr >= umem && uptr < umem + (ulong)_allocatedSize;
+        }
+
+        private void ReleaseUnmanagedResources()
+        {
+            if (_rawMemory != IntPtr.Zero)
+            {
+                Marshal.FreeHGlobal(_rawMemory);
+            }
+        }
+
+        public void Dispose()
+        {
+            ReleaseUnmanagedResources();
+            GC.SuppressFinalize(this);
+        }
+
+        ~EncodedStringsFifoDictionary()
+        {
+            ReleaseUnmanagedResources();
+        }
+    }
+}
diff --git a/src/runtime/perf_utils/EncodingGetStringPolyfill.cs b/src/runtime/perf_utils/EncodingGetStringPolyfill.cs
new file mode 100644
index 000000000..ac1d0ddcf
--- /dev/null
+++ b/src/runtime/perf_utils/EncodingGetStringPolyfill.cs
@@ -0,0 +1,53 @@
+using System;
+using System.Collections.Generic;
+using System.Reflection;
+using System.Runtime.InteropServices;
+using System.Text;
+
+namespace Python.Runtime
+{
+#if !NETSTANDARD
+    /// <summary>
+    /// This polyfill is thread unsafe.
+    /// </summary>
+    [CLSCompliant(false)]
+    public static class EncodingGetStringPolyfill
+    {
+        private static readonly MethodInfo PlatformGetStringMethodInfo =
+            typeof(Encoding).GetMethod(
+                "GetString",
+                BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic, null,
+                new[]
+                {
+                    typeof(byte*), typeof(int)
+                }, null);
+
+        private static readonly byte[] StdDecodeBuffer = PlatformGetStringMethodInfo == null ? new byte[1024 * 1024] : null;
+
+        private static Dictionary<Encoding, EncodingGetStringUnsafeDelegate> PlatformGetStringMethodsDelegatesCache = new Dictionary<Encoding, EncodingGetStringUnsafeDelegate>();
+
+        private unsafe delegate string EncodingGetStringUnsafeDelegate(byte* pstr, int size);
+
+        public unsafe static string GetString(this Encoding encoding, byte* pstr, int size)
+        {
+            if (PlatformGetStringMethodInfo != null)
+            {
+                EncodingGetStringUnsafeDelegate getStringDelegate;
+                if (!PlatformGetStringMethodsDelegatesCache.TryGetValue(encoding, out getStringDelegate))
+                {
+                    getStringDelegate =
+                        (EncodingGetStringUnsafeDelegate)Delegate.CreateDelegate(
+                            typeof(EncodingGetStringUnsafeDelegate), encoding, PlatformGetStringMethodInfo);
+                    PlatformGetStringMethodsDelegatesCache.Add(encoding, getStringDelegate);
+                }
+                return getStringDelegate(pstr, size);
+            }
+
+            byte[] buffer = size <= StdDecodeBuffer.Length ? StdDecodeBuffer : new byte[size];
+            Marshal.Copy((IntPtr)pstr, buffer, 0, size);
+            return encoding.GetString(buffer, 0, size);
+        }
+    }
+#endif
+
+}
diff --git a/src/runtime/perf_utils/FifoDictionary.cs b/src/runtime/perf_utils/FifoDictionary.cs
new file mode 100644
index 000000000..3af127de1
--- /dev/null
+++ b/src/runtime/perf_utils/FifoDictionary.cs
@@ -0,0 +1,62 @@
+using System;
+
+namespace Python.Runtime
+{
+    using System.Collections.Generic;
+    
+    public class FifoDictionary<TKey, TValue>
+    {
+        private readonly Dictionary<TKey, int> _innerDictionary;
+
+        private readonly KeyValuePair<TKey,TValue>[] _fifoList;
+
+        private bool _hasEmptySlots = true;
+
+        public FifoDictionary(int capacity)
+        {
+            if (capacity <= 0)
+            {
+                throw new ArgumentOutOfRangeException(nameof(capacity), "Capacity should be non-zero positive.");
+            }
+
+            _innerDictionary = new Dictionary<TKey, int>(capacity);
+            _fifoList = new KeyValuePair<TKey, TValue>[capacity];
+
+            Capacity = capacity;
+        }
+
+        public bool TryGetValue(TKey key, out TValue value)
+        {
+            int index;
+            if (_innerDictionary.TryGetValue(key, out index))
+            {
+                value =_fifoList[index].Value;
+                return true;
+            }
+
+            value = default(TValue);
+            return false;
+        }
+
+        public void AddUnsafe(TKey key, TValue value)
+        {
+            if (!_hasEmptySlots)
+            {
+                _innerDictionary.Remove(_fifoList[NextSlotToAdd].Key);
+            }
+            
+            _innerDictionary.Add(key, NextSlotToAdd);
+            _fifoList[NextSlotToAdd] = new KeyValuePair<TKey, TValue>(key, value);
+
+            NextSlotToAdd++;
+            if (NextSlotToAdd >= Capacity)
+            {
+                _hasEmptySlots = false;
+                NextSlotToAdd = 0;
+            }
+        }
+
+        public int NextSlotToAdd { get; private set; }
+        public int Capacity { get; }
+    }
+}
diff --git a/src/runtime/perf_utils/RawImmutableMemBlock.cs b/src/runtime/perf_utils/RawImmutableMemBlock.cs
new file mode 100644
index 000000000..6230bf5ec
--- /dev/null
+++ b/src/runtime/perf_utils/RawImmutableMemBlock.cs
@@ -0,0 +1,84 @@
+namespace Python.Runtime
+{
+    using System;
+
+    public struct RawImmutableMemBlock: IEquatable<RawImmutableMemBlock>
+    {
+        private readonly int _hash;
+
+        public RawImmutableMemBlock(IntPtr ptr, int size)
+        {
+            if (ptr == IntPtr.Zero)
+            {
+                throw new ArgumentException("Memory pointer should not be zero", nameof(ptr));
+            }
+
+            if (size < 0)
+            {
+                throw new ArgumentOutOfRangeException(nameof(size), "Size should be zero or positive.");
+            }
+
+            Ptr = ptr;
+            Size = size;
+            _hash = RawMemUtils.FastXorHash(ptr, size);
+        }
+
+        public RawImmutableMemBlock(RawImmutableMemBlock memBlock, IntPtr newPtr)
+        {
+            if (memBlock.Ptr == IntPtr.Zero)
+            {
+                throw new ArgumentException("Cannot copy non initialized RawImmutableMemBlock structure.", nameof(memBlock));
+            }
+
+            if (newPtr == IntPtr.Zero)
+            {
+                throw new ArgumentException("Cannot copy to zero pointer.");
+            }
+
+            RawMemUtils.CopyMemBlocks(memBlock.Ptr, newPtr, memBlock.Size);
+            Ptr = newPtr;
+            Size = memBlock.Size;
+            _hash = memBlock._hash;
+        }
+
+        public IntPtr Ptr { get; }
+
+        public int Size { get; }
+
+        public bool Equals(RawImmutableMemBlock other)
+        {
+            bool preEqual = _hash == other._hash && Size == other.Size;
+            if (!preEqual)
+            {
+                return false;
+            }
+
+            return RawMemUtils.CompareMemBlocks(Ptr, other.Ptr, Size);
+        }
+
+        /// <inheritdoc/> 
+        public override bool Equals(object obj)
+        {
+            return obj is RawImmutableMemBlock && Equals((RawImmutableMemBlock)obj);
+        }
+
+        /// <inheritdoc/>
+        public override int GetHashCode()
+        {
+            unchecked
+            {
+                return (_hash * 397) ^ Size;
+            }
+        }
+
+        public static bool operator ==(RawImmutableMemBlock left, RawImmutableMemBlock right)
+        {
+            return left.Equals(right);
+        }
+
+        public static bool operator !=(RawImmutableMemBlock left, RawImmutableMemBlock right)
+        {
+            return !left.Equals(right);
+        }
+    }
+}
diff --git a/src/runtime/perf_utils/RawMemUtils.cs b/src/runtime/perf_utils/RawMemUtils.cs
new file mode 100644
index 000000000..694acd1e8
--- /dev/null
+++ b/src/runtime/perf_utils/RawMemUtils.cs
@@ -0,0 +1,140 @@
+namespace Python.Runtime
+{
+    using System;
+
+    public static class RawMemUtils
+    {
+        public static unsafe bool CopyMemBlocks(IntPtr src, IntPtr dest, int size)
+        {
+            // XOR with 64 bit step
+            var p64_1 = (ulong*)src;
+            var p64_2 = (ulong*)dest;
+            int c64count = size >> 3;
+
+            int i = 0;
+            while (i <c64count)
+            {
+                p64_2[i] = p64_1[i];
+                i++;
+            }
+
+            var pn1 = (byte*)(src + (size & ~7));
+            var pn2 = (byte*)(dest + (size & ~7));
+
+            if ((size & 4) != 0)
+            {
+                *(uint*)pn2 = *(uint*)pn1;
+
+                pn1 += 4;
+                pn2 += 4;
+            }
+
+            if ((size & 2) != 0)
+            {
+                *(ushort*)pn2 = *(ushort*)pn1;
+
+                pn1 += 2;
+                pn2 += 2;
+            }
+
+            if ((size & 1) != 0)
+            {
+                *pn2 = *pn1;
+            }
+
+            return true;
+        }
+
+        public static unsafe bool CompareMemBlocks(IntPtr ptr1, IntPtr ptr2, int size)
+        {
+            // XOR with 64 bit step
+            var p64_1 = (ulong*)ptr1;
+            var p64_2 = (ulong*)ptr2;
+            var pn1 = (byte*)(ptr1 + (size & ~7));
+            var pn2 = (byte*)(ptr2 + (size & ~7));
+            while (p64_1 < pn1)
+            {
+                if (*p64_1 != *p64_2)
+                {
+                    return false;
+                }
+
+                p64_1++;
+                p64_2++;
+            }
+
+            if ((size & 4) != 0)
+            {
+                if (*(uint*)pn1 != *(uint*)pn2)
+                {
+                    return false;
+                }
+
+                pn1 += 4;
+                pn2 += 4;
+            }
+
+            if ((size & 2) != 0)
+            {
+                if (*(ushort*)pn1 != *(ushort*)pn2)
+                {
+                    return false;
+                }
+
+                pn1 += 2;
+                pn2 += 2;
+            }
+
+            if ((size & 1) != 0)
+            {
+                if (*pn1 != *pn2)
+                {
+                    return false;
+                }
+            }
+
+            return true;
+        }
+
+        /// <summary>
+        /// Calculating simple 32 bit xor hash for raw memory.
+        /// </summary>
+        /// <param name="mem">Memory pointer.</param>
+        /// <param name="size">Size to hash.</param>
+        /// <returns>32 bit hash the in signed int format.</returns>
+        public static unsafe int FastXorHash(IntPtr mem, int size)
+        {
+            unchecked
+            {
+                // XOR with 64 bit step
+                ulong r64 = 0;
+                var p64 = (ulong*)mem;
+                var pn = (byte*)(mem + (size & ~7));
+                while (p64 < pn)
+                {
+                    r64 ^= *p64++;
+                }
+
+                uint r32 = (uint)r64 ^ (uint)(r64 >> 32);
+                if ((size & 4) != 0)
+                {
+                    r32 ^= *(uint*)pn;
+                    pn += 4;
+                }
+
+                if ((size & 2) != 0)
+                {
+                    r32 ^= *(ushort*)pn;
+                    pn += 2;
+                }
+
+                if ((size & 1) != 0)
+                {
+                    r32 ^= *pn;
+                }
+
+                return (int)r32;
+            }
+        }
+    }
+}
diff --git a/src/runtime/perf_utils/RawMemoryFifoDictionary.cs b/src/runtime/perf_utils/RawMemoryFifoDictionary.cs
new file mode 100644
index 000000000..d845271d5
--- /dev/null
+++ b/src/runtime/perf_utils/RawMemoryFifoDictionary.cs
@@ -0,0 +1,59 @@
+namespace Python.Runtime
+{
+    using System;
+    using System.Runtime.InteropServices;
+
+    public class RawMemoryFifoDictionary<TValue> : IDisposable
+    {
+        private readonly FifoDictionary<RawImmutableMemBlock, TValue> _innerDictionary;
+
+        private readonly IntPtr _rawMemory;
+
+        public RawMemoryFifoDictionary(int capacity, int maxItemSize)
+        {
+            if (maxItemSize < 1)
+            {
+                throw new ArgumentOutOfRangeException(
+                    nameof(maxItemSize),
+                    "Maximum item size should be non-zero positive.");
+            }
+
+            MaxItemSize = maxItemSize;
+            _innerDictionary = new FifoDictionary<RawImmutableMemBlock, TValue>(capacity);
+            _rawMemory = Marshal.AllocHGlobal(maxItemSize*capacity);
+        }
+
+        ~RawMemoryFifoDictionary()
+        {
+            ReleaseUnmanagedResources();
+        }
+
+        public int MaxItemSize { get; }
+
+        public bool TryGetValue(RawImmutableMemBlock key, out TValue value)
+        {
+            return _innerDictionary.TryGetValue(key, out value);
+        }
+
+        public void AddUnsafe(RawImmutableMemBlock key, TValue value)
+        {
+            int nextSlot = _innerDictionary.NextSlotToAdd;
+            var localKey = new RawImmutableMemBlock(key, _rawMemory + (MaxItemSize * nextSlot));
+            _innerDictionary.AddUnsafe(localKey, value);
+        }
+
+        public void Dispose()
+        {
+            ReleaseUnmanagedResources();
+            GC.SuppressFinalize(this);
+        }
+
+        private void ReleaseUnmanagedResources()
+        {
+            if (_rawMemory != IntPtr.Zero)
+            {
+                Marshal.FreeHGlobal(_rawMemory);
+            }
+        }
+    }
+}
diff --git a/src/runtime/pyobject.cs b/src/runtime/pyobject.cs
index 7dca85545..02eca3c44 100644
--- a/src/runtime/pyobject.cs
+++ b/src/runtime/pyobject.cs
@@ -6,6 +6,9 @@
 
 namespace Python.Runtime
 {
+    using System.Reflection;
+    using System.Threading;
+
     /// <summary>
     /// Represents a generic Python object. The methods of this class are
     /// generally equivalent to the Python "abstract object API". See
@@ -261,9 +264,34 @@ public PyObject GetAttr(PyObject name)
             {
                 throw new PythonException();
             }
+
             return new PyObject(op);
         }
 
+        public T GetAttr<T>(string name)
+        {
+            IntPtr op = Runtime.PyObject_GetAttrString(obj, name);
+
+            if (op == IntPtr.Zero)
+            {
+                throw new PythonException();
+            }
+
+            try
+            {
+                object resultObj;
+                if (!Converter.ToManaged(op, typeof(T), out resultObj, false))
+                {
+                    throw new InvalidCastException("cannot convert object to target type");
+                }
+
+                return (T)resultObj;
+            }
+            finally
+            {
+                Runtime.XDecref(op);
+            }
+        }
 
         /// <summary>
         /// GetAttr Method
@@ -1089,6 +1117,12 @@ public override bool TryInvoke(InvokeBinder binder, object[] args, out object re
 
         public override bool TryConvert(ConvertBinder binder, out object result)
         {
+            if (typeof(PyObject).IsAssignableFrom(binder.Type))
+            {
+                result = this;
+                return true;
+            }
+
             return Converter.ToManaged(this.obj, binder.Type, out result, false);
         }
 
diff --git a/src/runtime/runtime.cs b/src/runtime/runtime.cs
index d4cb85583..7e93b65fe 100644
--- a/src/runtime/runtime.cs
+++ b/src/runtime/runtime.cs
@@ -266,6 +266,12 @@ public enum MachineType
         /// </summary>
         internal static readonly Encoding PyEncoding = _UCS == 2 ? Encoding.Unicode : Encoding.UTF32;
 
+        /// <summary>
+        /// 4Mb of Python strings to .Net strings cache.
+        /// </summary>
+        private static readonly RawMemoryFifoDictionary<string> UcsStringsInternDictionary =
+            new RawMemoryFifoDictionary<string>(10000, 100 * _UCS);
+
         /// <summary>
         /// Initialize the runtime...
         /// </summary>
@@ -1524,7 +1530,7 @@ internal static IntPtr PyUnicode_FromString(string s)
         /// </remarks>
         /// <param name="op">PyStringType or PyUnicodeType object to convert</param>
         /// <returns>Managed String</returns>
-        internal static string GetManagedString(IntPtr op)
+        internal static unsafe string GetManagedString(IntPtr op)
         {
             IntPtr type = PyObject_TYPE(op);
 
@@ -1541,9 +1547,20 @@ internal static string GetManagedString(IntPtr op)
                 int length = (int)PyUnicode_GetSize(op);
 
                 int size = length * _UCS;
-                var buffer = new byte[size];
-                Marshal.Copy(p, buffer, 0, size);
-                return PyEncoding.GetString(buffer, 0, size);
+                if (size <= UcsStringsInternDictionary.MaxItemSize)
+                {
+                    var ucsStringMemBlock = new RawImmutableMemBlock(p, size);
+                    string str;
+                    if (!UcsStringsInternDictionary.TryGetValue(ucsStringMemBlock, out str))
+                    {
+                        str = PyEncoding.GetString((byte*)p, size);
+                        UcsStringsInternDictionary.AddUnsafe(ucsStringMemBlock, str);
+                    }
+
+                    return str;
+                }
+
+                return PyEncoding.GetString((byte*)p, size);
             }
 
             return null;