Yeah, I've been focusing my effort recently on improving the performance issues in the game. There aren't any memory leaks, luckily, but I've had to do some more fine-tuning to the physics system (it's written from scratch).
The acceleration/deceleration are on purpose and aren't leaving. I know it's a controversial decision for a Mega Man game, but personally I enjoy the movement in the game.
I'll investigate the bustering and see if I can fix the random delay issue.
Not being able to shoot through walls is on purpose. I was inspired by X5 and X6.
Thanks for trying out the game and saying that it's promising! I know the game isn't perfect by any means. It's definitely a work in progress and I'm continuing to work on fine-tuning.