On my 33mhz (I'm almost, but not quite sure about the frequency) 486 SX (yeah ...) it ran OK until the levels where you'd get a lot of monsters. In those, I had to zoom in to the smallest possible screen size and even then it was barely acceptable.

So while the video is impressive and I couldn't do something like this myself, I was glad when I saw how bad it ran, as that computer of mine would a little bit more than 30yo today, so to have that beat by a 40yo printer controller would make me think I could have done something to have it run better back then!