It lagged like a female dog on certain levels when I tried playing on Chrome (literally less than 1 FPS) even after rebooting my computer and just having one browser window open to run it, and is a little choppy but playable on Firefox. It's not clear what's causing the lag from the DevTools Performance analytics, so sorry that's not much help.
Once you get past the performance issues, there are some pretty clever puzzles in here. I'm not as put off by the star system as the other reviewers, but I guess it wouldn't hurt to have all or most of the levels unlocked from the outset and have something like a mediumly-good ending for finishing all levels and a better ending for getting all stars if you feel like making them happy.