After 10+ hours of game into underground (gen a lot of pollution) (later the pollution has been neutralized), a bitters drill more and more rocks (including beyond the borders of the open area (show-path-requests) ) (and generate UPS drops (lags)).

Mod settings:
Biter rocks Disabled, Teleport bitters Disabled, resModifier 100, Teleport cooldown = 2

Debug info:
show-time-usage: Path finder: 7.714/6.873/16.759

the command to delete empty chunks did not help.

how i fix it: (kill underground surface):
move to underground,
/c game.player.print(game.player.surface.index) --getIndex
go to nauvis (leave underground surface)
remove all subways, underground shafts
/c game.surfaces[66].clear() --delete surface (66 - received index)

After fix: Path finder:
0.002/0.002/0.005

I can't really do anything about the pathing the only thing I can think of is limiting the amount of nests allowed per level.
Time permitting I will look at in weekend, will look to cull excess nests/biters

I noticed that sometimes nests are generated on the map, which stand on a small round piece of the floor, which does not have borders in the form of rocks, but has borders in the form of a black background. The biters around such a nest are calm and do not generate requests to find a way.

But, as soon as you connect the floor of this nest and the main surface with the help of rocks, the biters immediately begin to actively gnaw these rocks.
Idea:
I propose to make a setting at the launch of the mod, which will be responsible for the presence of rocks around the nests that are outside of certain coordinates.

Nests with rock borders will always be created on the initial area, and beyond the initial area - without borders. so that the player had to clean up at least the initial area (in settings set it's size) from the biters , and then did not suffer from performance losses.

P.S. ModMash New worlds it's so cool mod. Thanks)

setting added to limit amount of biters and nests, should help. rock boarders should always be there I'll have to see that fail before i can fix.
The rocks biters like to attack sort of have to be everywhere or hey just stall and do nothing.

bitters limit 50. path finder values now is 0,3/0,002/2,112 (ok). thanks!