Hmm, lag is kind of scary because it's something that I see frequently in builds of the game, but I assume it has something to do with my computer or that I frequently run it out of dropbox. I also seem to be the only one who gets lag because everyone I've talked to that's played the game has had it run fine, until now. I really don't know what to do about it though because it should run fine, and more often than not it does run fine.
The problem people have always had in the past is pressing jump right before changing directions, which leads to it not going off. I think the fix for this will be to add a ghost frame or two to let you 'convert' a normal jump into a backflip if the get the timing slightly off.
A little confused at your reasoning for disliking the new dive with it letting you go very far with the same momentum. In the previous two games, jumping out of a dive kept your momentum *AND* took you out of dive. This made keeping your dive momentum extremely easy, because all you had to do was jump out of your dive as soon as you hit the ground, and then dive again. If you messed it up (assuming you're trying to play the game quickly) there's not much of a punishment, since you'll have complete control of the player. With the dive in its current state, if you don't time your dive-jumps well enough, you'll lose momentum very quickly, which I think makes it a bit more interesting and skillful. However, it can be frustrating for any player to have to wait for momentum to naturally slow down before you get control back, so I'm still not totally sure on whether I'll keep this version of dive or revert to the old one.
The reason why charge isn't a run button where you build up speed over time is because I wanted it to be somewhat different from the speed booster in super metroid. I also don't want it to just replace dive as the best way to get over gaps or the best way to move quickly. The only reason why I don't let you dive while charging is because I like the jump-charge somersault animation too much and want to force people to look at it. However, being able to dive into a charge to conserve momentum is a very cool idea that I hadn't considered previously. I'll definitely experiment with that and see if I like it.
As for the damage boost thing, yes I know about it. I isn't a feature but I'm probably not going to fix it because there isn't anything inherently bad about it being in the game, and maybe speedrunners will like it. There's another unintentional bug in the game that I also probably won't fix for the same reason.