I have been tuning my xp11 installation to get the best frame rate. The xp11 Manual is very good (better than what was previously available) - but I have noticed what seems to be "bug" in the discussion of how to determine the optimum graphics settings. The manual says:
"We recommend putting the visual effects slider on its lowest setting, exiting the sim, restarting it, and noting the frame rate. From there, raise the slider up one level and repeat until the frame rate decreases. This is the point at which all of the video card’s RAM is being used. Back the texture resolution off to one level lower than where the decrease was noted and restart X‑Plane one more time."
I have found that the critical setting is the Texture Quality setting - and that the other settings (Visual Effects, Antialiasing, Number of World Objects and Reflection Detail) have a much smaller effect on frame rate. The manual doesn't mention it, but the settings screen shows the size of the Textures Loaded with the current settings. When that exceeds the capacity of your graphics card, frame rate will collapse. So, I think the correct approach to tuning is to start with the Texture Quality setting and not Visual Effects.
My system is an iMac Retina 27 running at 2880 x 1620 and the graphics system has 2GB of video RAM. With the payware KLAX scenery, sitting in the default B737 at 25R waiting to take off if I set the Texture Quality to High, it loads 2203MB of textures. Frame rate drops to 3 F/sec!. If I drop the Texture Quality to Medium, it loads 918 MB of textures and the frame rate increased to 25 F/sec. I can even increase Visual Effects to Max and still get 23 F/sec.
I suspect this kind of tuning will be a problem for many users - and I wish the manual discussion was better - and they really should mention the Texture Loaded information that the system supplies!
Am I missing something here? Have others found that Texture Quality is the critical adjustment? It's always possible that my system is different in some way - and tunes differently.