During space battles when you run at high speed ">>>", do you notice the red splotches for battle activity on your map accumulate until you go back to normal speed and they dissipate?
This, and other lagging effects, have happened to me several times towards the end of big campaigns. I never figured out a workaround and have always had to play the last portion through them. It makes me better appreciate the majority of the game where it's running properly.

Yes it does! and it is also near the end of a large scale campaign. Do you wipe out factions? Odd question, but i had a similar issues years back that was caused by too many active ai factions. In my current game noone has been wiped yet, i was hoping culling the imperials would improve performance. My other theory is that is based on player faction size (number of planets specifically) as it sems to fire around the same time as i expand after some play testing. Very good to know i can still play thru tho, i was really worried itd get worse and id waste time and still not finish. Thanks for the reply!