Understanding FPS, Frame Times & Smoothness
Estimated Lesson Length: 25–35 Minutes
Lesson Introduction
Welcome back.
So far in this module we’ve learnt how Microsoft Flight Simulator uses both your CPU and GPU, and how bottlenecks can affect overall performance.
Now we’re going to talk about something every flight simmer focuses on:
Frames Per Second, commonly known as FPS.
Almost every new flight simmer asks the same question:
“How do I get more FPS?”
While FPS is important, it’s only one part of the performance equation.
In fact, a simulator running at 30 stable FPS can often feel smoother than another running at 45 unstable FPS.
Today, you’ll learn why.
What Is FPS?
FPS stands for Frames Per Second.
Quite simply, it tells us how many individual images your computer creates every second.
Imagine watching a flipbook.
Each page contains a slightly different picture.
When you quickly flip through the pages…
Your eyes no longer see separate images.
Instead…
You see movement.
Your computer works exactly the same way.
Every second it draws lots of individual pictures called frames.
These frames are displayed so quickly that your brain sees continuous movement.
Example
If your simulator is running at:
30 FPS
Your computer is drawing
30 completely new images every second.
If your simulator is running at:
60 FPS
Your computer is drawing
60 new images every second.
The higher the FPS…
The more frequently the image updates.
Why FPS Matters
Higher FPS generally results in:
Smoother camera movement
Smoother panning
More responsive controls
Better tracking during approaches
Reduced input delay
However…
Higher FPS isn’t always the goal.
Consistency is.
The Biggest Myth In Flight Simulation
Many people believe:
“The higher my FPS, the better my simulator.”
This isn’t always true.
Let’s compare two systems.
Example One
30 FPS
Every frame arrives exactly on time.
Every frame takes roughly the same amount of time to render.
Movement feels smooth.
The aircraft moves consistently.
The camera pans smoothly.
Example Two
45 FPS
The simulator constantly jumps between:
45 FPS
↓
38 FPS
↓
50 FPS
↓
29 FPS
↓
47 FPS
↓
35 FPS
The FPS number is higher.
Yet…
The simulator feels worse.
Why?
Because the timing between frames isn’t consistent.
This brings us to one of the most important concepts in computer graphics.
Understanding Frame Pacing
Frame pacing describes how evenly your computer delivers each frame.
Imagine driving a car.
One driver travels at exactly
30 mph
the entire journey.
Smooth.
Predictable.
Comfortable.
Another driver constantly changes speed.
30 mph
↓
45 mph
↓
20 mph
↓
50 mph
↓
35 mph
Even though their average speed is higher…
The journey feels much rougher.
This is exactly what poor frame pacing feels like.
The simulator is constantly speeding up and slowing down.
Your eyes notice this immediately.
Why Frame Pacing Matters
Good frame pacing creates:
Smooth camera movement
Smooth landings
Stable taxiing
Consistent panning
Natural aircraft movement
Poor frame pacing creates:
Judder
Jerky movement
Small pauses
Uneven motion
Micro-stutters
Understanding Frame Time
Every frame takes a certain amount of time to create.
This is called
Frame Time
Frame Time is measured in
Milliseconds (ms)
Instead of asking:
“How many frames every second?”
Frame Time asks:
“How long did it take to create this frame?”
Example
30 FPS
Each frame takes approximately
33 milliseconds
to create.
60 FPS
Each frame takes approximately
16.7 milliseconds.
120 FPS
Each frame takes approximately
8.3 milliseconds.
The lower the frame time…
The smoother the simulator usually feels.
Why Frame Time Is More Important Than FPS
Imagine these two examples.
Simulator A
30 FPS
Every frame:
33 ms
33 ms
33 ms
33 ms
33 ms
Every frame arrives perfectly.
Movement feels smooth.
Simulator B
45 FPS
22 ms
40 ms
18 ms
52 ms
20 ms
12 ms
Although the FPS number is higher…
The frame delivery is inconsistent.
The simulator appears to stutter.
This is why experienced simmers often monitor frame times rather than FPS alone.
What Are Micro-Stutters?
A micro-stutter is a very brief interruption in smooth motion.
It may only last a fraction of a second.
Yet your eyes notice it immediately.
Examples include:
Small pause while taxiing.
Tiny freeze turning onto final.
Short hitch flying over London.
Brief hesitation while panning the camera.
These aren’t always caused by low FPS.
They’re often caused by inconsistent frame delivery.
Common Causes Of Micro-Stutters
CPU bottlenecks.
GPU bottlenecks.
Scenery loading.
Streaming photogrammetry.
Background applications.
Insufficient RAM.
VRAM limitations.
Shader compilation.
Windows updates.
Large Community folders.
Network delays while streaming scenery.
Each one interrupts consistent frame pacing.
Why 30 Stable FPS Often Feels Better Than 45 Unstable FPS
Let’s compare two approaches into Heathrow.
Pilot A
30 FPS
Frame times remain almost identical throughout the approach.
The aircraft remains smooth.
The landing flare feels predictable.
Camera movement remains fluid.
Pilot B
45 FPS
Frame times constantly change.
FPS jumps between
28
↓
51
↓
37
↓
45
↓
31
↓
48
Although the average FPS is higher…
The simulator constantly speeds up and slows down.
This creates a much rougher experience.
This is why many experienced flight simmers deliberately lock their simulator to a stable frame rate.
Consistency often provides a more enjoyable flying experience than chasing the highest possible FPS.
Measuring Frame Time
Open:
Developer Mode
↓
Display FPS
You’ll notice:
FPS
MainThread
GPU
Frame Time
Don’t just watch FPS.
Watch the frame times.
If they remain consistent…
The simulator will usually feel smooth.
If they constantly fluctuate…
You’ll begin noticing stutters.
Student Demonstration
Load:
PMDG 737
EGLL Heathrow
Live Weather
Taxi around the airport.
Observe:
FPS
Frame Times
MainThread
GPU
Notice how:
Even if FPS remains similar…
Sudden increases in frame time create visible stutters.
Student Exercise
Today’s exercise focuses on recognising smoothness rather than chasing numbers.
Step 1
Load your preferred aircraft at a busy airport.
Step 2
Enable the Developer Mode FPS Counter.
Step 3
Fly a complete landing.
Step 4
Observe:
- Does the simulator feel smooth throughout the approach?
- Do frame times remain consistent?
- Are there sudden pauses while turning onto final?
- Do you notice any small freezes when panning the camera?
Step 5
Record your observations in your Performance Baseline Worksheet.
Write down:
- Average FPS
- Approximate frame time (from the Developer Mode overlay)
- Did the approach feel smooth?
- Were there any noticeable micro-stutters?
- At what stage of the flight did they occur? (Taxi, take-off, cruise, approach or landing)
Lesson Summary
Congratulations.
You now understand one of the most overlooked aspects of Flight Simulator performance.
Remember:
FPS measures how many frames your computer produces every second.
Higher FPS does not always mean a smoother experience.
Stable frame pacing is often more important than a higher average FPS.
Frame time tells you how long each frame takes to render.
Consistent frame times produce smooth motion.
Micro-stutters are usually caused by inconsistent frame delivery rather than simply having “low FPS.”
As you progress through this course, our goal isn’t just to increase your FPS—it is to create a simulator that feels smooth, predictable and enjoyable to fly. That’s what real performance optimisation is all about.
Knowledge Check
- What does FPS measure?
- What is frame pacing?
- Why can 30 stable FPS feel smoother than 45 unstable FPS?
- What is frame time, and why is it important?
- Name three common causes of micro-stutters.
- When using the Developer Mode FPS overlay, why should you look at frame times as well as the FPS number?