You're using the wrong game engine for bullet hells then. I know with VXA and older, rendering a lot of sprites can be taxing on the frame rate. If we're talking pixel-based (not tile-based) movement patterns, definitely look into some other game engine.
If all you want is just a fair amount of projectiles moving on the screen, then Blizz-ABS will suffice. I don't have much experience with other ABS systems nor any knowledge of what exists. You should ask on the actual RM forums for guidance instead.