Why does my project slow down my browser?

https://snap.berkeley.edu/project?user=fridolinux&project=Farbspritzer.%20Ein%20Bildschirmschoner.
It's art. But why does it slow down my browser?

I don't know, but I do know that (for example) "repeat 22.5" will only repeat the script 22 times!

My best guess (I've heard of this being an issue sometimes) is the way that the browser handles the pen. The browser cache can sometimes handle bitmap really strangely (or whatever rendering type the pen feature is), and so it slows down because it's over-processing the pen. Not to mention that multiple tabs can slow it down. Close all unneeded programs and tabs. If that doesn't work, refresh the page. If THAT doesn't work, try restarting your device.

Maybe, sometimes, circles are not fully closed, so "fill" can "escape" to whole screen causing excessive load.

Oh, thanks, it was a left-over from some tests. Now it works longer, but it still crashes.

For me, after removing all "fill" instructions, project works forever.