Hallo,
I have the same (old) problem. FPS become less and less with the duration of the flight.
Example: LFMN (Nice) nach EDDP (Leipzig-Halle), PMDG 737-700; Daytime (LIFE); FEW CLOUDS; FL80 FPS Cockpit view (Track IR 5):
LFMN (Ramp 56C) > 90 FPS; Start Runway 04L >70 FPS; SID (TURIL 7A) 80 – 100 FPS; in Flight (FL80) 90-115 FPS – first 15 min
85-90 FPS – up to 90 min
60-70 FPS – until STAR
50-60 FPS STAR GOT1G
28-40 FPS IFR RW 08R
40-45 FPS Taxi to Ramp
50-55 FPS Ramp (109)
Start new Flight (1 minute later): EDDP, Ramp 109: > 70 FPS
No Limits for CPU, GPU and RAM during Fligth (last and temp.)
Graphics: 2560x1440; DLSS Super Res Quality; AMD FS 100; V-Sync OFF; NVIDIA Ref Low Latency ON+BOOST; HDR10 ON; DirectX 12; Global Rendering Quality ULTRA;’
Aircraft Traffic: OFF; Airport Vehicle D 20; Ground Aircraft D 5; Worker D 15; Leisure Boots 25;
Road Vehicles 20; Ships and F. 50; Fauna D 60;
DATA: Online Funct ON; Bing ON; Photogramm ON; Live Real Traffic OFF; Live Weather OFF; Multiplayer OFF;
Data Limitation OFF; BandWidth Limit UNLIMITED (2. Test 40 MBit/s);
Rolling Cache ON; 16 GB
PC: Ryzen 5800X3D; 32 GB Ram (DDR4, 3600) 3080Ti; Samsung 980Pro 1TB; Track IR 5; no OC
Win 11 (Software and driver up to date)