I did a test where I found the save file and manipulated it to only have 10 levels of speedup. Ran two instances of the game, reset the save on one, and checked if there was a speed difference. There is. It's insanely subtle. I recorded a gif here https://i.imgur.com/xJPyY25.g
It's not on repeat action so they're not accumulating stats either.
It's much more noticeable with 300 levels :3 https://i.imgur.com/pSSdA5W.gif
