Hmm, the lagging and zipping is not a behavior we've observed before, that's unfortunate. We have a note on the game page to play with Hardware Acceleration enabled if you're playing on Chrome, is it possible you have that turned off?
I THINK setting the mouse sensitivity to max is supposed to follow your native mouse speed perfectly or close to it, but my buddy (the programmer) will probably wanna weigh in here.
In any case, thanks so much for the kind words, and we're glad you were still able to get some enjoyment from playing! Appreciate the feedback too! :)