I came back to this game earlier in the week to check out the new content. The last time I played before then was in June. I'm really enjoying the new content but the performance has degraded quite a bit since then. I've got really choppy frame rates when driving, launching into space, or any quick traversing really. There also seems to be some issues with terrain pop-in and bits of floating terrain hanging around when they should have disappeared.
I brought down my settings all to medium, standard for cloud quality, and it doesn't seem to help much. Previously I was playing with much higher settings with less issues.
AMD FX 6300