How do I improve FPS and performance in Prepar3D?
To improve FPS in Prepar3D, we start by reducing the settings that hit performance hardest: shadows, dynamic lighting, reflections, antialiasing, AI traffic and cloud quality. Then we test at a demanding airport, keep add-ons under control, cap frames sensibly, and reset damaged config or shader cache files if stutters continue.
What settings improve FPS most in Prepar3D?
Not every slider matters equally. In Prepar3D, a few options usually do most of the damage, especially if we are flying a detailed airliner into a heavy airport with poor weather.
| Setting | Typical FPS impact | What to do first |
|---|---|---|
| Shadows | High | Reduce shadow quality, distance and the number of objects casting shadows |
| Dynamic lighting | High, especially at night | Lower or disable if night performance is poor |
| Reflections | High | Reduce update frequency or scope |
| Antialiasing | Medium to high, depends on resolution and GPU | Step down one level at a time |
| Cloud quality and draw distance | Medium to high | Reduce cloud quality before cutting terrain detail |
| AI traffic | High on CPU-heavy setups | Lower airline, GA, road and boat traffic |
| Autogen and scenery density | High | Lower autogen first, then scenery complexity |
| Texture resolution | Medium, can stress VRAM | Lower if using high-resolution aircraft and scenery textures |
If we want the fastest gains, shadows, traffic and autogen are usually the first places to look. They tend to cost more than mesh or basic terrain detail.
Step by step: how we tune Prepar3D for better performance
Create a worst-case test. Load a demanding aircraft at a detailed airport, with the weather you actually use. If we tune at a light default field on a clear day, the sim may still struggle when it really matters.
Lower shadows first. Aircraft, terrain and cloud shadows look good, but they are often one of the biggest drains on performance. Reducing shadow quality and distance usually gives a better return than cutting every setting across the board.
Reduce AI traffic. Airline, general aviation, airport vehicle, road and boat traffic all use CPU time. Busy traffic settings can cripple approach performance even on strong systems.
Trim autogen and scenery complexity. Dense buildings and vegetation are expensive, especially in built-up areas. We normally lower autogen before lowering mesh or texture detail, because autogen costs more and affects FPS more directly.
Ease off antialiasing and reflections. At higher monitor resolutions, aggressive antialiasing can hammer the GPU. Reflections are also costly, particularly if they update frequently.
Reduce cloud quality if weather causes slowdowns. If FPS falls sharply in overcast or stormy conditions, clouds are a likely culprit. Lowering cloud quality or draw distance often helps more than reducing terrain options.
Set a sensible frame rate target. An unlimited frame rate is not always best. In many setups, a reasonable cap can improve smoothness and reduce spikes, though the ideal value varies by hardware and add-ons.
Check add-ons one by one. Detailed aircraft, airport scenery, weather engines, traffic packages and camera tools can all affect performance. If a problem started recently, disable recent additions and retest.
Reset the shader cache and, if needed, rebuild the main config. Corrupt shaders or a badly tuned config can cause stutters, odd lighting issues or poor FPS. We do this carefully and only after noting our current settings.
Retest after each change. Change one thing at a time. If we move six sliders at once, we will not know what actually fixed the problem.
Low FPS or stutters? They are not always the same problem
People often say “low FPS” when they really mean “the sim feels jerky”. That distinction matters.
- Low FPS is a consistently low frame rate. This usually points to graphics settings, traffic, scenery density, weather load or demanding aircraft.
- Stutters are uneven frame delivery. The FPS counter may look acceptable, but the sim does not feel smooth. This can come from scenery loading, storage speed, background tasks, shader issues, add-ons, or an over-aggressive frame cap or sync setting.
- Pauses during turns or on approach often point to scenery, autogen, traffic or terrain loading rather than raw GPU power.
If the sim is smooth at 30 FPS but rough at 45, smoothness is the target, not the biggest number on the counter.
Should we edit the Prepar3D.cfg file?
Sometimes, but not as a first move. Too many old “tweaks” are copied from forum posts written for different versions, different hardware, or different sims entirely.
Our advice is simple:
- Use the in-sim settings first.
- If performance has become erratic, let Prepar3D rebuild its main config file and test again.
- Reset the shader cache if visuals or performance suddenly become abnormal after updates or major setting changes.
- Only apply manual config edits if we know exactly what they do and why we need them.
This is especially true across different Prepar3D generations. Older 32-bit releases were more sensitive to memory limits, while newer 64-bit releases handle memory far better. A tweak that helped one older setup may do nothing on a newer one, or make it worse.
Best Prepar3D settings for weak CPU vs weak GPU
If the CPU is the bottleneck
Prepar3D often leans hard on the CPU, particularly with complex scenery, traffic and glass-cockpit aircraft. If the main thread is overloaded, lowering pure GPU options may not help much.
- Reduce AI traffic
- Lower autogen density
- Lower scenery complexity
- Reduce draw distances where available
- Use fewer background utilities and overlays
If the GPU is the bottleneck
At higher resolutions, or with modern visual add-ons, the graphics card may be the limiting part.
- Lower antialiasing
- Reduce shadow quality
- Reduce reflections
- Lower cloud quality
- Lower texture resolution if VRAM use is high
A simple clue: if night lighting, shadows, rain and clouds hurt FPS most, the GPU is often under pressure. If big airports and heavy traffic hurt most, the CPU is often the issue.
Windows and hardware checks that actually matter
We should not ignore the basics. A badly configured PC can make a well-tuned sim run poorly.
- Power plan: Use a high-performance power profile so the CPU does not sit at conservative clocks.
- Background tasks: Close browsers, launchers, overlays, RGB tools and anything scanning or syncing in the background.
- Drivers: Keep graphics drivers stable and current, but avoid changing drivers every week if the current one works well.
- Storage: Installing the sim and major scenery on a fast SSD helps loading and can reduce texture and scenery pauses.
- Thermals: If the CPU or GPU is overheating, clocks can drop and performance falls with it.
- RAM and VRAM: Running out of memory causes hitching, texture issues and instability. High-resolution aircraft and scenery can fill VRAM quickly.
Why does Prepar3D run badly at some airports only?
Because not all scenery is equal. A default regional airport is light work. A handcrafted international hub with detailed terminals, dense ground clutter, high-resolution textures, dynamic lights and static aircraft is not.
Aircraft choice matters too. A simple GA aircraft can run smoothly where a systems-heavy airliner struggles. If FPS collapses only at certain airports, the problem is often the scenery-aircraft-weather combination rather than the whole sim.
Settings we usually lower last
Some settings affect visuals more than performance, or bring less improvement than people expect. We usually keep these for later unless we are troubleshooting aggressively:
- Mesh detail
- Basic terrain texture detail
- Water detail at moderate levels
- Minor visual extras that do not move the FPS needle much on our system
The aim is not a blurry sim. It is a balanced one.
When a full clean-up is worth doing
If performance suddenly became poor after months of normal use, and slider changes barely help, we would check for a deeper issue:
- A problematic new add-on
- A corrupted shader cache
- A damaged config file
- A graphics driver issue
- Windows updates or background software changing behaviour
At that point, a methodical clean-up and retest is often faster than endless micro-tweaks.
Practical rule of thumb
If we want the biggest performance gain in the least time, lower shadows, dynamic lighting, traffic, autogen and clouds before touching everything else. Test with the aircraft and airport we actually fly. Aim for stable, smooth performance rather than chasing the highest FPS number.
If you are experimenting with scenery and aircraft add-ons, keeping them organised and testing them one at a time is the safest approach. Our Prepar3D files area at https://flyawaysimulation.com/downloads/ is a useful place to keep track of what you have added and compare performance after each install.