I’ve had this happen twice now, both in the Salty 747 (on the only two flights over 5 hours I’ve flown since May 2021). Both times it started about exactly 6 hours into the flight. The first time it eventually became unplayable (~2 FPS) and crashed to desktop. After that, I increased the pagefile size and tried the NDU fix, but that did not help. On the second flight, after it started happening, I decided to divert and was able to land ~30-45 minutes later with the FPS still around 10 (except on short final momentarily ~2, which caused a very hard landing). It’s ridiculous that this has still not been fixed. With the CRJ this is not a problem but with the PMDG 737 coming this is surely going to cause problems on mid-range flights too.