Save file: https://drive.google.com/file/d/1k2WdDoUhEIS-wRkIgMHHCkR0OEjoVZDe/view?usp=sharing

Rampant is at the latest version
Biter evolution at about 81%
Rampant was added when the map itself was made

I'm playing Space Exploration with Krastorio 2. I have schall endgame evolution, bobs enemies, and rampant with the option new enemies enabled, 2 variations. At the start I wasn't lagging that much, could even run the game at 16x speed, but now it can't even get past 55 ups. I removed rampant (in a different save) and everything became smooth as butter, could even run the game at 16x speed again.

I'm expecting a solution to improve ups, I can remove schall endgame evolution and bobs enemies if needed. Removing rampant is a no go for me, I love this mod and I always include it whenever I play a modpack.

The mods I have are, (These are not all the mods, just the ones I think that are relevant to this thread.)
AAI Industry
AAI Signal Transmission
Alien Biomes with High res terrain
Bobs Adjustable Inserters, Assembling machines, Enemies, Mining, Power, and Warfare
Bullet Trails
Combat Mechanics Overhaul
Krastorio2
Rampant
Rampant Arsenal
Repair Turret
Schall Endgame Evolution
Space Exploration, with HR Graphics
Tree Collision

The next version should be better optimized, but if you are wanting to squeeze more UPS.
I would drop schall endgame
Bump the Ending enemy level in Rampants mod setting which will do roughly the same thing as schalls
The following mods are relatively expensive in terms of UPS when compared to Rampant in case you are wondering.
Construction drones, same cost as Rampant
EvoGUI, half as expensive as Rampant
TimeTools, half as expensive as Rampant
Repair Turrets, same cost as Rampant
Clock cost, 1/4 as expensive as Rampant
Even Distribution, half as expensive as Rampant