Hey all,
Looked into it on Facebook and no resolve, so I decided to put my troubles here. I start my sim fresh with the TBM at 40 FPS. After 1.5-2 hours of flying long distance, that frame rate drops below the acceptable 20 FPS. This is the only aircraft that has done this to me. I am on a Late 2014 iMac 4GHz i7, 12GB ram and AMD Radeon R9 M295X graphics with 4096 MB VRAM.
As for the sim, the staples regarding plugins and freeware scenery. However the problems don't occur when over that scenery, nor is the issue present on other aircraft (Zibo and Rotate MD-80).
I am a developer (I do web and server applications), so if you need an extra set of log files, I may be able to provide those.