Excellent performance, my old laptop can easily reach 120 FPS, about the game:
Is a nice attempt to take the essence of the first quake for my impression it doesn't allow to go faster by bunny hopping so basically you rely on the speed of your character and that's fine, I would consider changing the double jump in a bouncing so you can redirect your position and do cool dodge. Is this game gonna be all about speed? If that so I wonder if you are gonna add the crouching button, maybe it can be used for reaching higher speed with slide and stuff.
I've played at nightmare and I don't mind wave shooters but I notice that the gameplay it tends to be "press S and aim" and I think you should avoid this style cause it tends to limit the level design in long corridors where you must have enough space to dodge all the bullets/enemies.
Enemies should make noise continuously to understand if there are any enemy nearby and be vigilant (also to understand where are they because I got stuck 2 or 3 times finding hidden enemies), I noticed that the shit mosquito slow you down, usually old school FPS doesn't do that but if the player movement is too high that feature will punish people who rush toward levels, it depends on your side what you think feels better.
This game has potential, I hope to see your demo improved over the next DD.