I would teach Typescript. Being able to write the types down and hover things to see what types they are will definitely help them.
I think C would put them off. I also wouldn't go with Python, in case they want to do things like write games or make websites, which are common tasks you can do with Typescript but not very well with Python.
This is nonsense. Old software was not fast. Computers used to take minutes to start up. That's not an exaggeration. MS Word could easily take 30 seconds to open.
Obviously if you run it on modern hardware it's going to be lightning fast, but not because the authors cared more about performance and efficiency than we do now.