Microsoft Flight Simulator 2024

What's limiting you?

A frame is done when both halves are: the MainThread on the CPU builds it, the GPU draws it. The slower one sets your frame rate; the other one waits.

These are not real frame rates. Every FPS, millisecond and usage figure on this page is invented to show how the CPU and GPU interact. None of it is measured, and none of it tells you what you will actually get in the sim. For real numbers, see the benchmarks.
—FPS
Simulated · not real
 
MainThread — GPU —

Frame timelast five seconds, one point per frame

MainThread GPU Waiting

What Task Manager would showCPU and GPU usage, and why they mislead
CPU usage—
GPU usage—
MainThread is here right now

  • A low CPU number is not headroom. The frame waits on one thread, the MainThread. One thread flat out on a 16-thread chip adds only about 6% to the total, so a CPU can be what limits you while it reads a quarter busy.
  • No core reads 100% either. Windows keeps moving the MainThread between cores (watch the outline jump), so its load is smeared over several graphs that each look half idle. Switch to Airport to see it.
  • More threads help around the MainThread, not through it. Photogrammetry and scenery streaming do spread across many cores, so usage climbs in VFR. The frame still only comes as fast as the MainThread.
  • The GPU number is the more honest one. Near 99% means the GPU is the limit; well below means it is waiting. Better still, the sim's own FPS display in Developer Mode says "Limited by MainThread" outright.

Simulated like everything else here, to show the pattern, not a measurement.