I ran into some significant slowdowns, and running a quick profile it looks like the issue is with queued free item buffs - it appears to be checking every tick whether it can afford the next buff, and is spending a lot of time in get_cheapest_item_buff (a majority of which is in coin_tiers.multiply). And if it can't afford anything, this continues happening forever.

In my game, this is making hextorio take a constant 5ms per tick, with occasional spikes to 10ms - running /c __hextorio__ storage.item_buffs.free_buffs_remaining = 0 to clear the free item buff queue fixes the problem, and hextorio starts taking only 0.4ms per tick.

Some sort of buff cost caching, or simply don't check free buffs every tick, would likely help.

It's a state machine that is supposed to be spending one tick caching buffs that are available to upgrade as soon as either free_buffs_remaining becomes nonzero or the maximum achieved global net coin production increases. I suspect it's currently failing on that condition for some reason, so it's probably recomputing the available item buffs constantly. I can't fix it right now, but I will when I have the time.