a 2080S might be a little bit overstressed with
Otherwise, but havent tested yet, might be a theory that in bustrips a specific process is running bring more load in the CPU. But it can also be random and it is more because of the “cache” or the “time which is left” or a setting : I mean then its not related to a bushtrip, more like what some users report in a topic about loosing fps over time. I remember was often TLOD related and it depends on the area the users flight into, but not checked the topic state since a longer while.
Can you mentioned which stock Bushtrip you tried "where it happens allways and each time in your case " ?.. I have not much time, but may be I can try to reproduce the issue somewhen ( or another community members can do ).