WestWind Virtual Airlines

Vatsim has asked the X-Plane pilot clients to write code to automatically disconnect from the network when FPS falls below 20 frames per second. This due to X-Planes reducing the simulation rate to less than real-time when Frames fall below 20 frames per second.
https://forums.vatsim.net/viewtopic.php?f=157&t=80906

An important note that has apparently been glossed over by many readers is that the clients will not kick you the moment the frames drop below 20 FPS. It will only kick you once they drop down and stay there for a period of time (which isn't clearly stated, but I'm guessing it's somewhere like 10-30 seconds). They want to make sure that temporary stutters or momentary slowdowns due to loading in scenery/aircraft doesn't get you kicked off.

Also, to reiterate - this is not a punitive kick. You will be able to immediately reconnect to the network and stay connected as long as the frame rate stays above 20 FPS. This is simply being done to fix the problem Laminar Research kinda blindsided everyone with by introducing this "feature" without consultation of really anybody, much less fairly large (among their user base) Virtual ATC users.