Multiplayer lag issue

My friend and I both have plenty powerful PCs that run the game in singleplayer without issue. Somehow though, whenever we launch a multiplayer campaign, performance goes down the drain, especially in battles. It can easily take 5-10 seconds for a single second to go by on the battle timer and the units move like it (or even slower) we can both still move the camera just fine, our framerates are not the issue, just time passing by very slowly

Does anyone else have this issue? Or know a fix?