Howto:Improve framerates
Anything below about 15 frames per second (fps) is close to unusable, or at least, will not be enjoyable. Additionally, the more the framerate decreases, the more other features of the simulation will suffer. The current FlightGear software architecture is such that long rendering times (slow framerates) may prevent other parts of the flight simulator, such as the autopilot, from having sufficient CPU time to respond correctly in the context of the simulation.
FlightGear's framerate is influenced by various factors, including:
- scenery complexity (terrain,clouds, trees, particles, random 3D objects, multiplayer/AI traffic)
- cockpit complexity (2D vs. 3D)
- environmental options (eg. visibility, precipitation)
- FDM update interval
- AI scenarios
- aircraft speed (scenery paging)
You can disable most features that often adversely affect framerate. Here is a collection of settings that you may change to improve your framerate. Please note that some of these will only take effect if they're specified at startup and cannot be changed after the simulation has started.
3D Models
Contrary to what many people believe, the impact of high vertex-count models on framerate is fairly minimal. For graphic artists, the key things that should be avoided are:
- high resolution textures
- textures containing alpha
- textures themselves
- unwant polygons casting shadows
AI traffic
AI-traffic is computer controlled traffic, which includes traffic over the MP network. By turning of this function you're not able to see other aircraft. Most lag in FlightGear is caused by AI traffic. Especially heavy models need some time to load, eg the F-14 or the B-1B. Everytime a new aircraft enters the network your computer need to load that particular aircraft. That creates a lag. The bussier the place you fly the more lag you'll get; eg flying around KSFO will generate more lag than a flight near EGLL, since there is more traffic near KSFO.
External links
Optimizing file size, performance and streaming of 3D content