Ok I lied I kept it running in the background a bit while I was trying to get my game to build. It seems like the spawnrate did pick up a bit after a while, but I could stand AFK and still kill everything:
Generally I think the game needs more spectacle, too slow buildup and most of the skills are pretty dull. So more of everything basically. Most skills are too lowrange to be really useful. Way too easy to get stuck between enemies and beaten to death (if jump is on cooldown) which just isn't fun, a knockback on enemies on getting hit or getting a bit of free movement after getting hit would alleviate it. Skill upgrades are too incremental, you barely feel the difference one upgrade makes. Skills need a lot of balancing, really all you need is speed, lightning, and shield. Which are all too good compared to the other skills, kiting enemies with some movement speed is way too easy. There should be (more?) handcrafted wave spawns and not just spawn in one enemy at a time in a random position around you. If you have too many different kinds of skills they don't show up in the list:
I can't really comment on the performance though because I had a lot of stuff running in the background. Got a strange bug eventually, where the skill upgrade screen wouldn't go away:
Which did make me die eventually actually, probably to some boss getting stuck on a chest and shooting me to death. Although I couldn't see anything.