Game stutters when pawn searches for a new job

[faltonico]

I keep playing A16 very occasionally, and i did some testing to try to find out why my game stutters so much... It is a 17 year old colony.
I drafted all of my pawns but one.
The game ran fluidly! but when the undrafted pawn finished the work it was doing (carrying a chunk to a stockpile) the game stuttered very briefly (less than a second) the moment it dropped the chunk and it was fine again when it was in the way to get a new chunk.

It seems to me that the game searches really hard for a job to do, thus the stutter, but there is still a lot of crap to be hauled, and the paw is able.
Is there anything I can do to prevent or alleviate that? Can a mod be responsible for that behavior?

Any help is appreciated.