I've tested your game for a bit, and on a first glance, I think it worked like it should. I can move around and shoot. Collisions work okay too. One minor thing might perhaps be the fact that your bullets explode inside the walls, but only if you're really close to them. Not that big a deal, but I thought I point it out anyway.

I was not too impressed by the fps though. ~43fps does seem a bit low to me. However, (saving the worst for last ) I also tested your game fullscreen and I'm afraid that didn't go well at all. As soon as the resolution changed, the whole thing slowed down to a mere crawl. I couldn't see fps, but i'd be surprised if it was higher than 1 or 2 fps. Definitely a thing to look into.

Other than that, I think you're off to a good start.