Ah I found my mistake! I am playing on Vice and I had it set to NTSC, which seems to get 30 fps. When I switch to PAL I get the full 50 fps! Thanks for creating such a cheerful, if difficult, game :D
Congratulations on solving the issue!
(I had suspected that it might be NTSC, hence my question about the game being slower.)
Yes, the game is indeed difficult, but that's mostly because it's a single level (zone, in the game's terminology) as it had to fit in 16 kB. QUOD INIT EXIT IIo will have 5 zones of increasing difficulty.
Enjoy!