It's the same in my FSX-SE. Since the Aerosoft Airbus X and the new A318/319 my fps are really bad. But I have a lot of Addons inside, really much. GSX, EzDok v2, AS16, ATC-Pro X, UTLive, FTX Global and openLC and a lot of airports and a lot of aircraft. Usually I fly from EDDM or EDDH (taxi2gate addon and justsim). At these airports and at all the other addon-airports I have only 13-17 fps. Ok, then I deleted my fsx.cfg file. And again, bad fps. Then with tweak, so I maybe got 2-3 fps more. Very bad.
Then I made a test flight with the Ultralight in Friday Harbour.. 150 FPS!!!!! So my FSX is not the fault. Then I tested it with the project airbus in EDDH and EDDM. 30-40 fps!
So, Now I overclocked my CPU (AMD FX 8350 from 4,2 to 4,7 Ghz). Made now nearby ten flights with the airbus X at daylight with the same weather. In 2 flights there have been 21-28 fps. This is wonderful. But in 8 flights the fps droped down to 15-18 fps. That is too bad and not acceptable. Now I dont know, why the fps sometimes drop, sometimes not. The CPU is conctantly at 4,7 Ghz. SO what is the problem sometimes? Please help. I really need every frame per second!
AMD FX 8350 with 4,2 Ghz (OC 4,7Ghz)
Nvidia GeForce 1050
8 GB RAMs