Oh hey, thank you!
Yeah, I reduced some lag in the worst spots when doing the recent update, but never bothered to fully optimize. If I was smart, I'd have made all areas just larger to spread out the enemies more and keep things lag free.
I've been playing around with Pico8, but want to give GB Studio a try next, so it's been helpful learning about the limitations of the GameBoy's hardware by playing games like this. Delia seems like a great example of all the different kind of things the engine can do: top-down, platformer, shoot 'em up, etc. all rolled into one. I'm excited to give it a go myself.