Hi, I'm using Pythonnet to import proprietary python package from Windows Application. When my python package return a large byte array in C# world, the type conversion takes lot of time. To illustrate this long conversion time, I made a simple example: 1. A Python package with a method which return a byte array: class MyClass: @staticmethod def get_bytes_from_py(): array = np.arange(0, 720000, dtype=np.uint8) return bytes(array) 1. An application console to call my Python package and which convert 'bytes' type into 'byte[]' type static void Main(string[] args) { Runtime.PythonDLL = "c:\\Python38\\python38.dll"; PythonEngine.Initialize(); Stopwatch st = new Stopwatch(); st.Start(); using (Py.GIL()) { dynamic myPackage = Py.Import("mypackage"); dynamic myClass = myPackage.MyClass(); dynamic myPyByteArray = myClass.get_bytes_from_py(); long t0 = st.ElapsedMilliseconds; byte[] myCsharpByteArray = myPyByteArray; long t1 = st.ElapsedMilliseconds; Console.WriteLine("Conversion takes {0}ms", t1-t0); } st.Stop(); } 1. The console output: "Conversion takes 303ms" Is this the right way for this conversion? Environment: Python: v3.8.10 Pythonnet: * Pypi: v2.5.2 * Nuget : 3.0.0-preview2022-06-03 Windows 10 Pro .NET framework 4.7.2 Regards, Jordan GUILLOT