Scripts can't modify palettes? That's unfortunate news. (And, admittedly, I'd probably have actually bothered looking into doing it if they could. Oh well.)
Yes, since I have to define the color range of the cycling.
The lagginess comes from the cycling speed. You could use the maximum length of 231 to cycle palettes, but it takes something of about several seconds for it to kick in upon arriving; so the speed was set to 1. Ibuprofen is the same in this case for level 2/dark world.
Other than the cycling, it comes down to the user's graphics card, I believe. My previous near-decade-old machine didn't suffer any issues from it; the GFX card in the computer was only a couple of years old (as of this date). Other than that, it had a terrible single-core CPU, and just a couple GB of ram.
I'm running on a GPU from 2009, a Core 2 Duo, 3.25GB of RAM, and for some reason I still have this issue sometimes. (Seems to be with Firefox running period, for some weird reason.) However, this is on x86 Windows 7: I have not tried the Linux build of ZC on this machine yet.
I guess you could close Firefox to alleviate the issue. (I've personally just gotten used to it.) The really asinine thing about this is that on 1.92 b184... I don't suffer this issue at all. I have no idea. (Yes, 1.92 runs on Windows Vista and 7. I have NO IDEA why 90% of people say it doesn't work, I've never had an issue. Perhaps it's an x64 thing.)
Alternately, the palette cycle could be set to a slower speed: 2 or 3 may perhaps be workable? I'm not sure.