The hardest enemy was the end game FPS. And as can be seen on the ss in Flaise' post below when health goes over 1k, it starts to overlap the Armor text. Ended the game on exactly 6900 Armor, so that was nice!
I think it was "explosions leave poison clouds" with "2x explosions" upgrade that lead to it being as bad as it was, combined with several +duration upgrades to clouds. I had a frankly silly number of clouds that lasted long enough to still cover the screen on the next wave. I had a run that looked a lot more visually chaotic after, that only pushed my 7600x to like 70 degrees give or take. Whereas the first one was pushing it all the way up to 83, which is basically where it caps out with my cooling setup.
20 days ago(+1)
Hey thank you so much for the information!! I was able to recreate the exact scenario you described I reworked the collision checking logic for the poison clouds and changed how the game handles having multiple instances of the clouds. Plus put some cleanup logic in to remove redundant clouds which were simply wasting CPU time but not contributing to meaningful damage. It's performing much better on my machine now, but still need to do a little more testing.
The duration increases, along with enough damage to keep destroying enemies was leading to 500+ clouds stacking on-top of each other if circumstances played out right.. Thanks again for the help :)
19 days ago (+1)
Managed to find another slideshow 83 degree setup
This screenshot was from before it got really bad. But basically some combination of when heal do x and when crit do x and spamming ability cooldown every upgrade made it so that every time I used my ability the next ability would go off slightly faster, infinitely.
I never found the "create poison cloud on explosion" perk. Because I had the "explode on poison cloud ending" and "2x Explosions" so that would have been an infinite loop on its own that would get twice as bad every cycle.