been trying this myself, the expected happened, performance coming down below 15FPS, 8-10FPS at worst, mostly 25-20FPS, sometimes above, but the uneven frame rate (and stutters) are the real issue, it oscillates so wildly at times the average frame rate means nothing.
that aside, some flickering clouds, their colour and lightning is too even causing some lack of depth perception (at least for my eye); clouds look good from a certain angle and not so great form another, but overall they will definitely add another dimension; this test revived the notion that something's been lacking. not that great aesthetically speaking, big performance hit, but great potential there.
noted that the engine drops power dearly through thick clouds, preventing from climb and sometimes even maintaining altitude, maybe too exaggerated? didn't try the carburetor heater though.
thanks for sharing the test!
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q6600 2.4 oc 3.4 / GTX 570 1280MB / 4GB DDR2 800
SATA 3 / P5K-E Wi-Fi
Thrustmaster Flight Stick X