Overview of Libraries vs Sets
PERFLIGHT uses two different systems for organizing your addons: Libraries and Sets. Understanding the difference between them is key to getting the most out of the app.
Written By Jim Thompson
Last updated 2 months ago
Libraries: Where Your Addons Live
Libraries are physical folder locations on your computer where addons are stored. When you add a library to PERFLIGHT, you're pointing it to a folder on your hard drive (like D:\MSFS Addons\Scenery or E:\Flight Sim\Aircraft). PERFLIGHT scans these folders to discover the addons inside.
Think of libraries as your filing cabinet - they represent the actual storage locations of your addon files. Every addon in PERFLIGHT belongs to exactly one library, based on where it's physically installed.

Key points about Libraries:
Libraries are folder paths on your filesystem
Each addon belongs to one library only
The Libraries drawer lets you filter your view - showing or hiding addons from specific libraries
Toggling library visibility doesn't enable or disable addons, it just controls what you see on screen
Use libraries to organize where you store different types of addons
Sets: How You Group Your Addons
Sets are virtual collections of addons that you create for quick activation. Unlike libraries, Sets aren't tied to folder locations - they're custom groups you define based on how you want to use your addons together.
Think of Sets as playlists for your addons. You might create a Set called "Hawaii VFR" containing your Hawaiian scenery, a bush plane, and some weather enhancement addons. Or an "Airliner Ops" Set with your favorite airliners, airport scenery, and GSX profiles.

Key points about Sets:
Sets are virtual groupings you create
An addon can belong to multiple Sets
Activating a Set enables all the addons in that group
Deactivating a Set disables all its addons
Sets change the actual enabled/disabled state of your addons, affecting what loads in the simulator
The Critical Difference
When to Use Each
Use Libraries to:
Organize your addon storage by type, source, or drive
Filter your view when browsing a large collection
Keep track of where things are physically installed
Use Sets to:
Prepare for specific flight scenarios
Quickly switch between addon configurations
Group addons that you commonly use together
Manage which addons are active for your next flight
Working Together
Libraries and Sets complement each other. You might have your addons organized into libraries by category (Aircraft, Scenery, Utilities), but then create Sets that pull from multiple libraries for specific use cases.
For example:
Libraries: Aircraft, US Scenery, Europe Scenery, Utilities
Sets: "US Tour" (includes addons from Aircraft + US Scenery + Utilities), "European Ops" (includes addons from Aircraft + Europe Scenery + Utilities)
This gives you the best of both worlds - organized storage and flexible activation.