turns out I DIDN'T start the timer late, that was from a previous (failed) attempt
I'm actually not sure what settings affected it because I changed them at random, and at some point the game ran mostly fine, but would completely freeze at around 10 minutes of playtime and make my computer run slow also. I ended up using a different program altogether - D3DWindower, which so far caused no problems
Looks like that was, indeed, DxWnd's fault, after tweaking some settings the speed looks to be the same
I've tried to race the current record by Finsterhund, but their game seems to be slightly faster than mine - check the video
In it, I start off earlier than him, making mostly the same actions (if not faster ones), but eventually he still catches up and even finishes the level faster.
I'm running on Windows 10 with DxWnd - anyone else noticed something similar?