Hmm, I'm not sure why this would cause lag. I didn't notice any in my own testing, but I haven't tested much since the recent updates to GB Studio. Are you using an emulator to test, and if so, which one?
I'm using Mesen. A downloadable sample scene would be a great way to get to know this plugin better, since there's no documentation :) I'll test it on real hardware once I find the time to recap my SNES.
Tested with Super Game Boy and Super Game Boy 2 in a empty scene where this script (see attached pic) is the only one in the scene. It produced the same amount of frozen frames unfortunately. I'm using the latest versions of GB Studio, Platformer+ and Super Gameboy SFX.
