Simply clicking on fleets and moving the camera from one system map to another causes the screen to freeze for 2-3 seconds each time (which becomes increasingly annoying). It even freezes before dialogue begins. This issue has worsened the more the campaign has progressed. You need to optimize or change how your assets are loaded (I get these same hangups when i put !factorials! into my crappy calculator, which is a lel).
Quite honestly, the campaign map should be DRASTICALLY less resource intensive than the actual ship combat (which runs fine on my pc on MAX resolution and graphics settings). Considering the campaign map is a bunch of fixed models and text with limited effects (such as when ships warp between systems), whereas the actual ship combat has moving models and particle effects and physics and things have to dynamically render and there's much more going on, and I experience 0 freezing or lag whatsoever in the circumstance of actual gameplay. Operating on this premise, I fail to see the reason, mathematically, that the campaign map should have hangups at all.