I am playing with the full mod mash (which is awesome, to be honest), however this particular underground mod makes the game so laggy starting when I place the first underground shaft. I experienced no such experience on any other mod, the game start to jerk like every 10 seconds. Any idea why and how to fix it? Thank you.

To be clear continually or just once. If jyst when placing its due to generating a new surface which has the same size as the parent map nauvis.
If not I need more detail other mods or a save or log do i can dig in.