It's running on windows, which makes the "real-time" argument void. And if you are recording anything your hardware better have a built in buffer and real time

It's running on windows, which makes the "real-time" argument void. And if you are recording anything your hardware better have a built in buffer and real time stamps already. It's not exactly like you are bit-banging things to a serial port... However i agree that making the hardware interface in c would be the best option. But in most cases your hardware would already come with this and using P/Invoke to call it from C# is then piece of cake. It's hard to give a definite answer since the OP doesn't specify if the application also has hardware output or just recording. And what are the time constants? Are we talking seconds or microseconds?