[BlurBusters]

Author here.

You need to keep the GPU free to work on the game; doing CRT simulation at 60fps at 480Hz requires brand 8 new frames per videogame frame, and it's doing a bunch of math operations per subpixel per refresh cycle. If you run it at full resolution 2560x1440x480x3, that's a lot of processing.

Especially since it also uses a variable-MPRT algorithm that cascades brightest pixels to subsequent refresh cycles;

That's why it's coming to RetroArch and best to process the low-resolution framebuffers first, before scaling and sending through CRT filters/simulated curvatures/etc.

Most retro games are just 320x240.