Yes, and map size too especially Earth part size.Too bad, I've never seen the end game stuff yet. Back to the beginning, I guess.
The number of AIs is related to the graphics memory running out?
Also less RAM is used with smaller maps too.
Game with 5 AIs has around 2x shorter turn times than with 10 AIs if amount of cities per AI isn't changed.
If you want to play to end as quick as possible try my spacemap without AI.
Kations space maps are good too.
You wont get late game toys on generated maps.