Other people's code is awful, and your own code from months previous counts as someone else's. With this and the festive spirit in mind, I dug up a canvas snow demo I made two years ago to see how bad my code really was.
Turns out the performance landscape has changed quite a bit, but after applying a couple of workarounds, best practices, and memory management, I got the demo running smoother than it ever did.
Ugh, I can't believe I just wrote "performance landscape". Anyway...