I've played this game in the past and had the same issue and never found a fix. I have changed all the compatibility settings and messed with changing the renderer to ts-ddraw and others. I've also added the videobackbuffer=no to the correct folders. Offline skirmish play is completely fine and this only effects online custom games for me. There is a stutter freeze which only lasts for less than a second but is almost constant making it feel very skippy. The other issue is like a very low FPS issue to where its almost impossible to play. My units move extremely slow and buildings are a pain to build up.
Note this is a brand new pc I built within the last 2 months. rtx 2080, ryzen 7 2700x, 32gb ram, m2 ssd etc the pc should not be having any issues with the game, this is the same problem I had on my 10 year old computer.