I have tested several maps with cheating ai at the default 1.075 and at the max 2.0. With 2000-3000 units and still ran 3x-4x with 4x speed setting all the way to end game with nukes and experimentals. I recently played a game on ian's cross just me and cheating AI but i had cheats set to on and basically played with unlimited mass and power to get insane number of units going and all ran smooth , no slow down all the way until i nuked the AI to death. but the AI was sending waves of experimentals not single but multiple together. Also, the AI was sending nukes in front of my waves of units to try and time an explosion to take them out. The sorian AI never did that stuff. was awesome! best part is the no simspeed slowdown late game all the way to conclusion. The game without LOUD mod simspeed crawls under those conditions, looks like slideshow. lol
I don't play against other people. I prefer AI. sometimes I do play coop with a friend locally over lan. The two of us against AI.