I was playing in-browser. I can imagine the downloaded version might run better. (Though I'd ultimately be playing on a slower computer, so it might not run better XD... I'm extremely picky about downloads on my primary workstation, I appreciate you having a web-build!)
The part where it started snowing had a lag so long and intense I thought the game had crashed, but waited a minute and it came back so I was able to continue. Otherwise, the lag built slowly as the game progressed. But never so bad that I couldn't win. However, if the enemies had been more aggressive I probably couldn't have completed the game. By the end I was crashing into them regularly as the lag made it tough to precisely move about.