It’s all very well to to watch “f-act” in the screen frame-rate display as you fly. However it’s constantly changing. The best way to study your frame rate is to have a list of all these figures and maybe put them into a spreadsheet. You can easily do this by clicking on the Developer menu pull-down option and click on Show FPS Test recorder.
In the window that pops up you can click “Start recording” at any point during your flight and when you have recorded enough, click Stop recording. X-Plane then writes out a file showing the stats:
You can find this file in the …X-Plane 12\Output\replays folder as a .fps file. Although it has a .fps extension, its a text file readable in any text editor. It’s laid out as a CSV file [comma-separated values file] with spaces instead of commas so it’s easy to import into a spreadsheet.
Of course, you can always set the data output to record to a file as well as show on the screen, but this is often overkill since the entire flight’s frame rate is recorded resulting in an enormous file:
