Well slowing down while there are a lot of bots fighting in sight will be normal, yeah, since you have to wait for everyone to fire before it's your turn again (if they aren't visible or within in audible range their combat is resolved instantly to avoid unnecessary slowdown).
As for your save though, I've confirmed it's definite non-combat slowdown, and before opening it had also guessed that it's in Factory
. This sometimes happens there, the known cause being excessive pathfinding because either there are simply so many bots on such massive maps, or some bots got stuck or are unable to access your location (doesn't seem to be the case here).
One reason players can be more sensitive to it is if you're moving slowly, meaning more robots get to move in between your turns. You're moving at 120, so not very fast, but technically it shouldn't slow down quite this much even at 120.
Thanks for the save I'll investigate this later to see if we can resolve the underlying cause (beyond simply speeding up pathfinding,
again, which is also something I've wanted to do for a while).