It appears that somewhere near the endgame if you have many systems with big influence areas they start partially flickering in random segments, I suppose because of multiple overlapping. And that makes the game hardly playable as it is both epileptic and hardly recognizable.

As example: multiple AIs had their systems in close proximity to each other and when I've got into a war with one of them I couldn't properly oppose it as influence areas were constantly flickering and I always was stopped either by cold war areas that block system invading or closed borders. That happened in all my latest campaigns.

I'm playing on the latest Steam version with all DLC's.