Ok I read the avsim post. Sincerely i did not try to remove all plugins (but i did for some). At the moment I was able to fly at 20/25 fps with setting all low except clouds size (at circa 25/30 %) but i'm still experiencing heavy fps drops almost randomly during flight, and i also lowered some x-plane settings a step down. The fact is that with HDR off or on the situation is almost the same, apart from the small fps reduction when hdr is active. Today i tried to load my LIMC scenery (that it's quite heavy, but it's near my real home and the weather was absolutely clear today), with real weather the sky was all clear also in the sim, but suddenly the fps dropped dramatically to 5/7 without any action in the sim...only loading plane...and the sky was completely clear!!! no clouds, no cirrus, no contrails. At that moment I started to think there was something really wrong with SMP, and not related with 3D rendering...but probably some incompatibility. I also noticed that CPU usage was really increased after SMP installation... I'm not trolling, but i'm a bit frustrated I cannot manage to use this plugin in the right way, when in he past i solved many problems with x-plane, sometimes speaking with plugins' and sceneries' authors, sometimes alone. For now I'll try the following procedure to reset SMP: 1) uninstall SMP 2) remove all plugins 3) clean up windows 8 a bit more (some registry and cache cleaning...) 4) fire-up x-plane and close 5) install SMP 6) fire up x-plane, activate SMP and close 7) remove GIZMO (If I understand well this is used only for activation...and it leaves a sort of taskbar at the right of the screen...that is quite annoying) 8) start x-plane and make a flight 9) start adding plugins... I think this is the last solution I can try to make this plugin working well... I'll report results here...