I guess this could potentially kill your UPS (lots of chests), but technically you only have to sort them when somebody is looking at a chest's contents...

Actually all you need to explain the needed time is Hofstadter's Law: https://en.wikipedia.org/wiki/Hofstadter%27s_law

I experienced heavy desync-problems using this mod, especially (actually, only) when loading a savegame. So far (not extensively tested) I was able to fix this, by changing the actors/fishery.lua in line 17 to: global.fish_in_chunk[chunk_name] = global.fish_in_chunk[chunk_name] + 5 --+ math.random(0...