I got a performance improvement tonight while at Ini’s EGLL by disabling in windows (11) Opitimizations for Windowed Games in windows graphics settings (yes the sim is actually a borderless windowed game), but apparently this setting applies only to dx10/dx11 titles and is not relevant and perhaps even detrimental to dx12 games. I had been seeing 16-17FPS this morning before FG and after changing this setting saw 22-24FPS befire FG tonight at EGLL (with ai traffic). Give it a go and see if it does anything for you.
I also note that the A350 has a ‘performance mode’ option in the efb that can be selected to reduce some texture res. I haven’t had time to test that option out yet.
I had a very smooth flight from egll to egpf tonight. All in all I’m quite impressed with the A350.