Thanks for your detailed feedback, it is much appreciated!
I'm surprised you were able to beat the Halls of Pain while having 10fps, that really must've been painful. To address your balance concerns, only a few enemies are preset (like the Bloodsoaked guard and one of the Skinless Cultists who drops the green shield). Every other named enemy with buffs is randomly created and placed, with their stats determined at runtime - the ice zombie is one of those. The overall balance is still a bit too hard for many players (even if they have OK performance), so that's subject to change.
For me, the fun in these games is making the best build out of what resources you are given and trying to beat the game that way. Something you get unlucky and lose - for me that's part of the appeal. Things like a resupply hub are planned (although not a town, and not with limitless supplies)
You also provided a ton of technical bug reports, which will help me out immensely! I'll get all of these fixed up once DD ends.
Thanks again for the feedback, and I'm sorry you didn't have a particularly enjoyable experience. I hope the next time I submit it will be more enjoyable, should you decide to give it a go