Measuring Add-on Performance

Estimated Lesson Time: 45–60 Minutes

Lesson Overview

By now, you’ve learned how airports, aircraft and weather influence Microsoft Flight Simulator performance.

In this lesson, we’ll focus on another major factor:

Third-party add-ons.

One of the greatest strengths of Microsoft Flight Simulator is its thriving add-on ecosystem. From detailed airports and advanced aircraft to traffic packages, ground handling, navigation tools and ATC enhancements, add-ons can dramatically improve realism.

However, every add-on introduces additional workload.

Some place extra demand on the CPU.

Others primarily affect the GPU.

Some consume additional RAM or VRAM, while others have almost no measurable impact at all.

The key is learning how to identify which add-on is responsible for a change in performance.

Professional optimisation means testing one change at a time and measuring the results—not assuming every stutter is caused by the simulator itself.

Lesson Objectives

By the end of this lesson you will understand:

How different add-ons affect performance.

Which add-ons mainly affect the CPU.

Which add-ons mainly affect the GPU.

Which add-ons increase RAM and VRAM usage.

How to isolate the impact of individual add-ons.

How to benchmark with and without add-ons.

Why Add-ons Affect Performance

Every add-on introduces extra work for your PC.

Depending on the add-on, this may include:

Additional scenery.
More detailed textures.
Extra aircraft models.
AI calculations.
Navigation data.
Background applications.
Ground service logic.
Live traffic processing.

The more work introduced, the greater the impact on performance.

Understanding what each add-on does helps you predict how it will affect your system.

1. Airport Add-ons

Detailed airports are among the most demanding add-ons available.

Examples include:

iniBuilds airports.
FlyTampa airports.
Aerosoft airports.
Orbx airports.

These airports often include:

High-resolution textures.
Detailed terminal interiors.
Animated jetways.
Ground clutter.
Custom lighting.
Static aircraft.
Service vehicles.

CPU Impact

Moderate to High.

The CPU manages:

Object placement.
Airport logic.
Animation updates.
Additional draw calls.

GPU Impact

High.

The GPU renders:

Extra buildings.
More detailed textures.
Lighting.
Shadows.
Reflections.

VRAM

Usually increases because of higher resolution textures.

2. Liveries

Liveries replace aircraft textures with different airline paint schemes.

Most liveries have very little impact when used on your own aircraft.

However, large AI traffic packages containing hundreds of liveries can increase:

VRAM usage.
Loading times.
Storage requirements.

CPU Impact

Very Low.

GPU Impact

Low.

VRAM

Slight increase depending on texture resolution and the number of unique aircraft visible.

3. GSX

GSX adds realistic ground handling services.

Examples include:

Passenger boarding.
Catering.
Fuel trucks.
Pushback.
Baggage loading.
Ground animations.

CPU Impact

Moderate.

GSX continuously controls:

Vehicle movement.
Passenger animations.
Ground service logic.

GPU Impact

Low to Moderate.

The GPU renders additional animated objects and vehicles.

RAM Usage

Slight increase.

Typical Performance

Most users experience only a small FPS reduction, but very busy airports with multiple active services can increase CPU workload.

4. FSLTL

FSLTL provides live AI aircraft and realistic airline traffic.

This is one of the most demanding add-ons in terms of CPU usage.

CPU Impact

High.

The CPU must calculate:

AI flight paths.
Taxi logic.
Navigation.
Lighting.
Aircraft behaviour.

GPU Impact

Moderate.

The GPU renders:

Aircraft models.
Liveries.
Navigation lights.
Shadows.

VRAM

Moderate increase.

Large numbers of AI aircraft require additional graphics memory.

5. BeyondATC

BeyondATC enhances air traffic control by introducing advanced communication and traffic management.

CPU Impact

Moderate.

The software performs:

Speech processing.
Traffic management.
Flight monitoring.

GPU Impact

Minimal.

Most processing occurs on the CPU.

Performance

Generally has a modest performance impact but may become more noticeable alongside heavy AI traffic.

6. AutoFPS

AutoFPS is different from most add-ons.

Rather than adding workload, it dynamically adjusts simulator settings to maintain smoother performance.

For example, it may automatically change:

Terrain LOD.
Object LOD.
Traffic settings.

based on current system load.

CPU Impact

Very Low.

GPU Impact

Indirect.

By lowering demanding settings during busy situations, GPU workload can decrease.

Important

Because AutoFPS changes simulator settings dynamically, benchmarking becomes difficult.

When performing controlled benchmarks, disable dynamic optimisation tools unless you are specifically testing them.

7. Toolbar Pushback

Toolbar Pushback replaces the default pushback system with a more flexible alternative.

CPU Impact

Very Low.

GPU Impact

Negligible.

Performance

Most users will see no measurable FPS difference.

8. Charts & Electronic Flight Bags

Applications such as:

Navigraph Charts.
SimBrief integration.
Electronic Flight Bags (EFBs).

provide flight planning and navigation information.

CPU Impact

Generally Low.

GPU Impact

Very Low.

RAM Usage

Slight increase.

Running these applications externally may use additional system memory, but the impact is usually modest on modern PCs.

9. Navigraph

Navigraph provides:

Updated navigation databases.
Charts.
Flight planning integration.

The navigation database itself has virtually no measurable impact on simulator performance.

Any small performance cost usually comes from companion applications rather than the data itself.

10. Community Folder

The Community Folder is where most third-party content is installed.

Over time, many users accumulate hundreds of add-ons.

Not every add-on is active at all times, but large Community folders can:

Increase loading times.
Make troubleshooting more difficult.
Increase the chance of add-on conflicts.

A well-organised Community folder helps simplify performance testing.

Many users temporarily disable non-essential add-ons when benchmarking to create a consistent test environment.

How to Isolate Add-on Impact

The most effective way to measure an add-on is to change one thing at a time.

Example:

Benchmark 1

Default simulator.

Benchmark 2

Same flight.

Same airport.

Same weather.

Enable GSX only.

Benchmark 3

Same conditions.

Enable FSLTL only.

Benchmark 4

Same conditions.

Enable both.

Now you can identify exactly how each add-on influences performance.

Example Comparison

Default Simulator

Average FPS:

GPU:

94%

MainThread:

Occasional limitation.

GSX Enabled

Average FPS:

MainThread:

Slight increase.

FSLTL Enabled

Average FPS:

MainThread:

Frequently Limited.

Detailed Airport Installed

Average FPS:

GPU:

99%

VRAM:

Increased.

These are illustrative examples only. Your own results will vary depending on hardware, simulator version and add-on configuration.

Common Mistakes

Installing multiple new add-ons before benchmarking.

Comparing different airports.

Using Live Weather.

Forgetting to record Community Folder changes.

Assuming every performance issue is caused by one add-on.

Ignoring CPU and GPU monitoring.

Student Exercise

Today you’re going to measure the impact of your installed add-ons.

Step 1

Load your permanent benchmark flight.

Keep the same:

Airport.
Aircraft.
Parking Stand.
Weather.
Time of Day.
Graphics Settings.

Step 2

Run the benchmark with no additional third-party add-ons enabled where practical.

Record:

Average FPS.
1% Lows.
GPU Utilisation.
VRAM Usage.
MainThread Status.

Step 3

Enable one add-on.

Examples:

GSX.
FSLTL.
A detailed airport.
BeyondATC.

Run the same benchmark again.

Step 4

Repeat for each major add-on you regularly use.

Do not enable multiple new add-ons at once.

Step 5

Compare your results.

Ask yourself:

Which add-on produced the largest FPS change?
Which increased CPU workload the most?
Which increased GPU utilisation?
Which used the most VRAM?
Which had little or no measurable impact?

Document your findings in your benchmark database.

Student Checklist

Baseline benchmark completed.

Individual add-ons tested separately.

CPU behaviour recorded.

GPU behaviour recorded.

VRAM usage monitored.

Benchmark database updated.

Add-on impact understood.

Lesson Summary

Congratulations.

You now understand how third-party add-ons influence Microsoft Flight Simulator performance.

Remember:

Every add-on introduces some form of workload, but not all workloads are the same.
Detailed scenery tends to increase GPU demand and VRAM usage, while AI traffic and advanced simulation tools often place greater demands on the CPU.
Utility add-ons such as pushback tools or navigation databases generally have a much smaller performance impact than scenery or traffic packages.
The only reliable way to measure an add-on’s effect is to benchmark it in isolation under controlled conditions.
A structured testing process allows you to identify the true performance cost of each add-on and build a simulator that balances realism with smooth, consistent performance.

Knowledge Check

Why do different add-ons affect performance in different ways?
Which types of add-ons generally place the greatest demand on the CPU?
Why do detailed airport add-ons often increase VRAM usage?
Why should dynamic optimisation tools such as AutoFPS be disabled during controlled benchmarks?
How can a large Community Folder influence simulator performance and troubleshooting?
Why should only one add-on be introduced between benchmark runs?
Which performance metrics should you monitor when testing an add-on?
Based on your own benchmarks, which add-on had the greatest impact on your simulator, and what evidence supports your conclusion?

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