I've made it pretty much a habit at this point to code, from scratch, everything in-game with at least one global speed modifier in mind (like, my own global.gameSpeed variable). Everything that happens, such as movement and actions can then be easily modified by multiplying it by that number, so you could set everything to double speed, or slow down everything by 90% with one line of code. It makes it a lot easier to tweak overall gamespeed / feel down the line, and it's also a very neat way of implementing bullet-time like effects, should the need arise. I recommend trying to get into this habit. The good thing is you haven't started yet, as it's a pain to do in a game that's already quite a bit along in development.