The important question is: How to reduce FPS drops in teamgames.
1v1 has no fps drops throughout the 1h game. 2v2 has some, once both sides are at 100 cap. 3v3 starts getting stuttery at 15-20 minute mark. 4v4 is a general shit***w unless you have a brutal system.
My guess is that larger game modes increase the two largest time killers: FOW and Pathing.
vCOH calc'ed FOW like once every second. COH2 seems to do it almost every frame. And it takes a bit of time to do if done on the CPU as opposed to the GPU. Dont know where Relic does it. Maybe they moved to GPU for Coh2.
Pathing just takes time in general. You have to guess all the possible pathways and find the shortest difference. So bigger modes = more units pathing, more units blocking pathing, larger maps so you need to do this calc a lot more, etc. This is probably all CPU based for 2013 code? Units also seem to favor red cover so vehicles get a speed boost on roads. But vCoh fans remember units that had to path long distances would just stop halfway there because they could not figure out a path anymore and their stored path got blocked.
Larger game modes also have more artillery/tanks/mortars/AT going which means adjusting terrain height, terrain cover, terrain impass(pathing), terrain precise map(pathing unit width), terrain texturing, etc all on the fly while things are blowing up.
I am always amazed the game runs at all. So kudos to Relic for the performance they got out of it. My point is dont get your hopes up too high.