Hello there, Thank you for your reply; I did some tests yesterday, I had no crach in several flight, remaining around 20-30 fps .... I lowered the clouds minimum and maximum slider , cloud coverage remained satisfying and beautiful. Increasing the maximum details of clouds does not affect , nor godrays, I have no drop in performance, it seems that only the number of clouds makes my fps drop (i have detail at max , reflections, god rays , high res everywhere) ... It must be said that there were many stormy areas these days (I'm using only real wheater), it immediately triggers a mini freeze and slowdown my FPS .... I have X-Plane 10.30 b8, HDR on détail max, jar a 320 and photosceneries X16 everywhere ( X17 in airport areas).... My config : I5 3550 3,3ghzradeon 7950 3 Go Vram8 Go Ram. I am not sure that the overall issues from other users are essentially due to ram....