I added this mod and my mega base went from stable 40 UPS to 19/20.

What could be causing this?

PS: looking at the code, it seems that you could put in some performance tweaks:
- if you change the item count to 200 (1 stack) instead of 10, and lower the refresh rate (to say 10 seconds, which still doubles the amount of items). It will greatly improve things.
- Another thing you could do is split the updates of the chests between several ticks, so, instead of updating all the chests on the same tick you divide them in chunks. Example if you have 10 chests and you update every 10 seconds, you can split to update each every second.

I checked what it was doing and for some reason it was updating on every tick, not every 60 like it was told. I have released a new version to run every 180 ticks or about every 30 seconds.

Awesome, thanks :D