Introduction
Before we begin changing any settings in Microsoft Flight Simulator, it’s important to understand the hardware that’s running your simulator.
Many people believe buying the most expensive graphics card will automatically solve performance problems. In reality, Microsoft Flight Simulator relies on every major component inside your computer working together.
Think of your PC like a real aircraft.
The CPU is the pilot.
The GPU is the windscreen.
RAM is your working memory.
Your SSD is the aircraft’s storage compartment.
If one part can’t keep up, the whole simulator slows down.
Let’s begin with arguably the most important component.
Understanding The CPU
What is a CPU?
The CPU stands for Central Processing Unit.
It is often referred to as the “brain” of your computer because it is responsible for performing millions of calculations every second.
Unlike many games that mainly rely on the graphics card, Microsoft Flight Simulator performs an enormous amount of real-time simulation.
Every second your CPU is calculating thousands of things simultaneously.
Simulation Calculations
When you’re flying, the simulator isn’t simply displaying an aircraft in the sky.
It’s constantly calculating:
- Aircraft position
- Aircraft speed
- Aircraft altitude
- Wind direction
- Wind strength
- Temperature
- Air pressure
- Lift
- Drag
- Fuel usage
- Aircraft weight
- Flight controls
- Ground interaction
Every movement of your joystick or yoke is instantly recalculated.
Every gust of wind changes how your aircraft behaves.
Every second these calculations are updated.
Your CPU performs all of this.
AI Traffic
AI Traffic refers to all of the aircraft the simulator creates around you.
For every AI aircraft the simulator must calculate:
- Taxi routes
- Pushback
- Runway sequencing
- Take-off roll
- Climb
- Cruise
- Descents
- Landings
- Parking positions
Imagine Heathrow Airport.
There might be 80 aircraft moving simultaneously.
Every single aircraft has its own flight plan.
Every aircraft must avoid collisions.
Every aircraft follows taxi instructions.
Every aircraft updates several times every second.
Your CPU calculates every one of these movements.
This is one reason large airports reduce performance.
Flight Model
The flight model is how your aircraft actually flies.
Every second the simulator calculates:
- Lift
- Drag
- Stall speed
- Centre of gravity
- Engine thrust
- Fuel weight
- Aircraft balance
- Flap position
- Gear position
- Wind effects
Rather than simply moving the aircraft forward like an arcade game, Flight Simulator calculates realistic physics.
This is incredibly demanding.
Aircraft Systems
Modern aircraft such as the PMDG 737, Fenix A320 or iniBuilds A350 contain thousands of working systems.
Examples include:
Electrical systems
Hydraulic systems
Fuel systems
Air conditioning
Pressurisation
Navigation computers
Autopilot
FMC calculations
Weather radar
Cabin announcements
Warning systems
Each one is continuously updating.
Your CPU performs these calculations every second.
This is why complex aircraft often perform worse than a default Cessna.
Glass Cockpit Updates
Modern aircraft display information using digital screens.
Examples include:
Primary Flight Display (PFD)
Navigation Display (ND)
Engine Displays
Electronic Flight Bag (EFB)
Each display refreshes constantly.
It updates:
Aircraft position
Speed
Altitude
Navigation
Weather
Traffic
Flight plan
Fuel
Warnings
The more displays updating, the more work your CPU performs.
Terrain Calculations
One of Flight Simulator’s biggest achievements is recreating the world.
As you fly, the simulator constantly loads:
Roads
Trees
Buildings
Mountains
Cities
Photogrammetry
Satellite imagery
Water
Bridges
Power lines
Terrain isn’t loaded all at once.
It loads continuously as you fly.
Your CPU decides:
What should load
When it loads
What should unload
How detailed it should be
This becomes especially demanding over large cities like London or New York.
Why Is Microsoft Flight Simulator CPU Limited?
Many people buy an expensive graphics card expecting huge FPS increases.
Sometimes nothing changes.
Why?
Because the CPU is waiting to finish all of its calculations before the graphics card can begin rendering the next frame.
Imagine a restaurant.
The CPU is the chef.
The GPU is the waiter.
If the chef hasn’t cooked the meal yet…
The waiter has nothing to deliver.
The waiter can be incredibly fast…
But he’s still waiting for the chef.
This is exactly what happens in Microsoft Flight Simulator.
If your CPU cannot complete its work quickly enough, your GPU sits waiting.
This is known as a CPU bottleneck.
Understanding The GPU
The GPU stands for Graphics Processing Unit.
While the CPU performs calculations…
The GPU draws everything you see on your monitor.
Think of the GPU as the artist.
It turns calculations into images.
Clouds
Clouds are one of the most demanding graphical features in Flight Simulator.
The GPU renders:
Cloud density
Lighting
Cloud shadows
Weather effects
Volumetric clouds
Storms
Higher cloud settings require more GPU power.
Lighting
Lighting includes:
Sunlight
Airport lighting
Cockpit lighting
Landing lights
Taxi lights
Street lights
Reflections
Every light source must be rendered by the GPU.
Night flying often increases GPU workload.
Reflections
Reflections include:
Aircraft windows
Cockpit displays
Water
Buildings
Wet runways
More realistic reflections require more GPU power.
Textures
Textures are the detailed images wrapped around objects.
Examples:
Runways
Taxiways
Buildings
Aircraft paint
Cockpit panels
Clouds
Higher resolution textures look sharper.
They also use more VRAM.
Anti-Aliasing
Anti-aliasing smooths jagged edges.
Without anti-aliasing…
Aircraft wings and buildings appear rough.
With anti-aliasing…
Edges become smooth.
Different methods include:
TAA
DLSS
FSR
Each has advantages and disadvantages.
These will be covered later.
Shadows
Shadows are calculated every frame.
Examples:
Aircraft shadows
Cloud shadows
Building shadows
Cockpit shadows
Higher shadow settings increase GPU workload significantly.
Understanding VRAM
VRAM stands for Video Random Access Memory.
It is memory built directly into your graphics card.
Think of VRAM as your GPU’s workspace.
The GPU stores:
Textures
Clouds
Terrain
Shadows
Models
Aircraft
Lighting information
inside VRAM.
If VRAM becomes full…
The graphics card must repeatedly fetch data from your computer’s RAM.
This is much slower.
Symptoms include:
Stutters
Texture pop-in
FPS drops
Long loading pauses
Generally speaking:
8GB VRAM works well for 1080p.
12GB is better for 1440p.
16GB+ provides additional headroom for higher resolutions and large add-on libraries.
The amount of VRAM you need also depends on the aircraft, scenery and settings you’re using.
GPU Utilisation
GPU utilisation tells us how hard the graphics card is working.
If GPU utilisation is:
95–100%
Your graphics card is working at full capacity.
This is normal if you’re GPU-limited.
If GPU utilisation is only:
40–60%
but FPS is still low…
The CPU is likely preventing the GPU from working harder.
This is another sign of a CPU bottleneck.
Understanding RAM
RAM stands for Random Access Memory.
RAM temporarily stores information the simulator needs immediately.
Instead of repeatedly loading data from your SSD…
RAM keeps it instantly available.
Think of RAM like your desk at work.
Your SSD is the filing cabinet.
Your desk is RAM.
You keep the documents you’re currently using on your desk because it’s much faster than walking back to the filing cabinet every few seconds.
16GB RAM
Suitable for:
Basic flying
Smaller airports
Default aircraft
Light add-on usage
You may notice limitations when using demanding aircraft and scenery together.
32GB RAM
Currently the sweet spot for many MSFS users.
Allows:
Complex aircraft
Large airports
Photogrammetry
Multiple background applications
Large community folders
64GB RAM
Best suited for:
Heavy scenery collections
Video creators
Multiple monitors
Virtual Reality
Professional-level simulator setups
For many users, 32GB is sufficient, while 64GB offers extra headroom for very demanding scenarios.
Why Low RAM Causes Stutters
When RAM fills up…
Windows starts moving information onto your SSD.
This process is called paging.
Even a fast SSD is slower than RAM.
The result is:
Micro-stutters
Loading pauses
Texture loading delays
Reduced performance
Storage
Your simulator must constantly read data from storage.
The faster your storage…
The faster the simulator loads.
Hard Drive (HDD)
A traditional hard drive uses spinning magnetic disks.
Advantages:
Large capacity
Lower cost
Disadvantages:
Very slow loading
Long startup times
Slower scenery loading
More stutters
Not recommended for Microsoft Flight Simulator.
SSD (Solid State Drive)
An SSD stores data electronically with no moving parts.
Benefits:
Much faster loading
Reduced stutters
Quicker updates
Improved responsiveness
Recommended as the minimum storage type for Flight Simulator.
NVMe SSD
An NVMe SSD is significantly faster than a traditional SATA SSD.
Benefits:
Very fast loading times
Faster scenery streaming
Improved installation speeds
Reduced waiting when launching the simulator
While an NVMe drive won’t usually increase FPS on its own, it can improve the overall experience by reducing loading times and helping scenery load more smoothly.
Scenery Streaming
One of Flight Simulator’s most impressive features is its ability to stream scenery from Microsoft’s servers as you fly.
Instead of storing every building and every landscape on your PC, the simulator downloads scenery as needed.
For this to work well, you need:
- A stable internet connection.
- Fast storage to save and retrieve streamed data efficiently.
- Enough RAM and VRAM to hold the scenery while you’re flying.
If any of these become a bottleneck, you may notice delayed terrain loading, blurry scenery, or pauses as new areas load.
This lesson gives students the technical foundation they’ll need before moving on to practical optimisation. Later lessons can then refer back to these concepts—for example, explaining why reducing Terrain LOD helps a CPU-limited system or why lowering cloud quality eases GPU load—so the advice feels logical rather than a list of settings to copy.