Insanely Low Framerate For Multiplayer

So for the last few months when I’ve been trying to play an online match with my gf, the lag/frame rate has been insane.
She is playing on an old laptop and the game works perfectly fine, yet I am playing on a new pc, using a Geforce RTX 3070, Ryzen 5900x and 64GB ram and I suffer a frame rate drop to 1 or 2 all the time.

At the start of a match, it works ok. But as soon as there are 6 players with 200 pop limit each and lots of buildings, it becomes unplayable. The delay between me giving a command and the men moving is 3 minutes or more. Yet my gf can play just fine without any of this.

If i play offline, it works perfectly fine - I can play against 7 AI with us all having a pop limit of 500. So is there something really wrong with the servers?
I’ve tried contacting the official support but they said they haven’t a clue what to do about it.