Thank you very much!
I'm pretty sure it's not the parallax causing lag, but the enemies being too close together so the DMG has to process two of them at once...
As for the jump pads, just hold the jump button, you're not supposed to time it lol
And yes, the whip is a static invisible projectile, but to make it feel better, the whip hitbox is 4 pixels larger than the actual whip in every direction, and the hitbox only lasts 0.1 second, so it doesn't have enough time to drift too much from the whip while you're mid-jump, oh and, setting the walk and run speeds while on the ground to 0 for the duration of the attack also helps, but don't forget to reset it to the normal movement speed when the attack is done!
And as for the kappas (turtles) jumping out, it's actually pretty simple! I adjust their speed mid-movement to simulate gravity! 8 pixels below the peak I half the movement speed, then I hold them in mid-air for half a second, then move them back down 8 pixels still at halved speed, then I set the speed back to normal and move the rest of the way down! Oh, and the splashes are a static projectile with no collisions!