TorchScript vs C++ Frontend

Hi @ptrblck, @yf225, @albanD, @Michael_Suo, saw your comments on other similar posts so I thought perhaps you could provide some valuable input.

I also reviewed the PyTorch C++ Deployment Story: 2019 post. But I am not clear on difference on speed between TorchScript and pure C++. Also, I could use some input on limitations of TorchScript. I read on some posts that LSTM and maybe some conditional constructs if/loops are not supported (or require extra effort that I am not completely clear on).

I would appreciate any help.