Improve FlightGear graphics and FPS with practical settings for resolution, clouds, shadows, scenery, GPU drivers, stutters and CPU bottlenecks.
To improve FlightGear graphics and performance, start with an up-to-date OpenGL driver and ensure it uses the dedicated GPU, if fitted. Establish a repeatable baseline, then reduce resolution, shadows, clouds, visibility and scenery density until frame time is stable. Spend the recovered headroom on anti-aliasing, texture filtering and better scenery.
What should I change first in FlightGear?
Change the expensive graphics settings in a controlled order rather than moving every slider at once. Option names and available effects vary between FlightGear builds and rendering pipelines, but the tuning method remains the same.
- Create a repeatable test. Use the same default aircraft, airport, cockpit view, time and clear-weather conditions. Disable AI traffic and multiplayer models for the first test, and let any TerraSync activity finish before judging performance.
- Check the graphics driver and GPU. Install a proper vendor driver with OpenGL support rather than relying on a basic operating-system driver. On a dual-GPU laptop, assign FlightGear to the high-performance GPU and test while connected to mains power.
- Reduce the largest GPU costs. Lower display or render resolution first, followed by shadows, cloud detail, anti-aliasing and advanced renderer effects. Change one option at a time and repeat the same view.
- Reduce scene complexity if FPS barely changes. Cut visibility distance, random buildings, vegetation, scenery detail, AI traffic and multiplayer aircraft. These settings can burden the processor as well as the graphics card.
- Add visual quality back selectively. Restore texture filtering and moderate anti-aliasing before expensive shadows, dense clouds or extreme visibility. Keep the combination that produces consistent frame time, not merely the highest FPS while parked.
A mistake we see constantly is testing each change at a different airport or in a different aircraft. A detailed airliner at a large airport cannot be compared fairly with a light aircraft over sparse terrain.
Which FlightGear settings affect FPS most?
Resolution, shadows, clouds and scene complexity usually deliver the largest performance gains, while anisotropic filtering often sharpens runway and terrain textures at a smaller cost.
| Setting | What it improves | Typical cost | Best adjustment |
|---|---|---|---|
| Resolution or render scale | Overall sharpness | High GPU cost, especially at 4K | Lower it when FPS rises substantially during a resolution test |
| Anti-aliasing | Jagged aircraft and building edges | Moderate to high GPU cost | Use a moderate level rather than the maximum |
| Anisotropic filtering | Runway and ground textures viewed at an angle | Usually low on a suitable GPU | Prioritise this before costly effects |
| Shadows and renderer effects | Depth, lighting and cockpit appearance | Often high | Reduce shadow quality or distance before disabling shadows entirely |
| Clouds and weather detail | Atmosphere and weather depiction | Often high and situation-dependent | Reduce cloud density or detail when poor weather causes the slowdown |
| Visibility and scenery objects | Long-range terrain, buildings and vegetation | CPU, GPU and memory cost | Reduce gradually around dense airports and cities |
| Texture quality | Surface and cockpit detail | Mainly video memory | Keep it high unless video memory pressure causes pauses or texture swapping |
| AI and multiplayer models | Airport and online traffic | Mostly simulation and scene-processing cost | Disable for diagnosis, then restore only as much traffic as needed |
Extra camera windows, mirrors and aircraft displays can require additional rendering work. If one particular aircraft performs badly, compare it with a simple default aircraft before changing global graphics settings.
How do I tell whether FlightGear is CPU- or GPU-limited?
A controlled resolution test provides the quickest answer: run the same view, then repeat it at a much lower resolution.
- FPS rises clearly: the GPU is the likely limit. Reduce resolution, anti-aliasing, shadows, clouds and advanced effects.
- FPS changes very little: the main simulation or scenery workload is more likely limiting performance. Reduce AI traffic, multiplayer models, object density, vegetation, visibility and aircraft complexity.
- Average FPS is acceptable but pauses remain: investigate scenery downloads, storage speed, insufficient RAM or video memory, shader compilation and thermal throttling.
Temporarily remove VSync or a frame cap while diagnosing the bottleneck. An FPS value locked to the display refresh rate, or a fraction of it, does not necessarily indicate poor performance. Restore VSync afterwards if it gives smoother motion without objectionable control latency.
If FlightGear remains slow at low settings, compare the machine, memory and OpenGL support against our practical FlightGear hardware and driver guidance. More graphics memory helps with high-resolution textures and dense scenery, but it will not cure a processor bottleneck.
How can I make FlightGear look better without losing much FPS?
The safest visual upgrades are good texture filtering, restrained anti-aliasing and better source scenery, added in that order after performance is stable.
- Use the display's native resolution when the GPU has enough headroom; otherwise lower resolution one step and retain texture filtering for clearer runways.
- Apply anti-aliasing through FlightGear first. Forcing a second anti-aliasing mode through the graphics driver can waste performance or have no effect under some renderers.
- Increase texture quality only while video-memory use remains comfortable. Sudden pauses and delayed texture loading are stronger warning signs than average FPS.
- Add shadows, cloud detail and long visibility last. These produce attractive screenshots but are poor priorities when frame time is already unstable.
Higher-detail terrain can improve coastlines, elevations and ground detail more effectively than maxing every shader option. Our FlightGear HD world scenery download is an offline option, but it requires substantial storage and can increase memory and rendering demands in detailed areas.
TerraSync and manually installed scenery are scenery sources, not universal graphics presets. Search-path order matters, and an older package can mask the scenery you intended to load; follow our instructions for installing scenery and setting its search paths if terrain changes do not appear.
Which FlightGear renderer should I use?
Start with the default renderer selected by your FlightGear build, because it is the best baseline for supported effects and troubleshooting.
Some builds expose a Compositor-based renderer alongside older rendering modes. Their settings are not interchangeable: an effect may be unavailable, renamed or ignored under another pipeline. Avoid combining command-line flags copied from guides written for a different renderer.
If the modern renderer causes a black screen, missing effects or severe artefacts, first remove forced driver overrides and test a default aircraft. If the build offers a lighter or legacy renderer, use it as a diagnostic fallback for older OpenGL hardware, then compare performance under identical conditions.
Why does FlightGear still stutter when FPS is high?
Stutter with a good average frame rate usually comes from scenery loading, memory pressure, shader work or an unusually complex aircraft rather than raw rendering speed.
- TerraSync is downloading tiles: allow the area to finish downloading, then repeat the flight. Reducing visibility can also limit how much scenery must be loaded around the aircraft.
- Video memory is full: lower texture quality, resolution, anti-aliasing or dense HD scenery. Once textures spill out of fast graphics memory, pauses can be more noticeable than the FPS loss.
- Storage or RAM is saturated: close memory-heavy programs and keep active scenery on faster storage where possible. Large overlapping scenery packages also deserve checking.
- The aircraft is the cause: test the same airport with a simple default aircraft. Detailed instruments, mirrors, displays and systems can create a bottleneck even when external scenery is modest.
- Shaders are being prepared: the first use of a renderer or effect may pause briefly. Repeat the same test before assuming every flight will behave identically.
- The laptop is throttling: use mains power, an appropriate performance profile and unobstructed cooling. Thermal throttling often appears after several minutes rather than immediately after launch.
For a balanced setup, keep AI traffic disabled until the simulator is smooth, use moderate anti-aliasing, retain useful texture filtering, and tune clouds, shadows and scenery density for the busiest airport you regularly fly from. Settings that work only over empty terrain are not a reliable performance preset.