LeanFPS1. Save the real old value
Before a change, LeanFPS reads the current value and writes it to a journal on disk. If the value did not exist, that is recorded too, so undo deletes it instead of guessing a default.
Record first, then change
A safe game optimizer: every change can be undone
A safe game optimizer should leave your PC exactly as it found it when you ask. LeanFPS saves the real value of every setting before it changes it, undoes game-time changes on its own, and never touches security settings or your files.
Five rules that make LeanFPS a safe game optimizer
2. Undo one at a time
Every tweak has its own switch. Turning it off restores only that tweak. Restore all puts back everything at once.
3. Reverse game-time changes
Tweaks that run while you play are undone in the opposite order when the game exits, the same way Linux’s Feral GameMode does it.
4. Recover after a crash
If Windows or LeanFPS stops mid-game, the next start finds the open session in the journal and reverses it first.
5. Roll back on failure
If one step of a tweak fails, the steps already done are rolled back, so you are never left with a half-applied change.
Tested on real Windows
On every change to the app, our build pipeline applies, checks and reverts every tweak on a Windows virtual machine and confirms the original values come back.
One session, step by step
Drag the timeline to see what a safe game optimizer changes when a game starts and what it puts back when the game closes.
| Setting | Value now |
|---|---|
| Power mode | Balanced |
| Game priority | – |
| Background apps | Normal |
| Mouse acceleration | On |
| Sleep and screen off | Allowed |
Saved previous values
- Power modeBalanced
- Background appsNormal
- Mouse accelerationOn
- Sleep and screen offAllowed
Nothing changed yet.
Example from a laptop playing a competitive shooter. Desktops keep the power plan change between sessions until you turn it off.
Things LeanFPS never changes
These are common in other game optimizer tools. Each either lowers your security or has no measurable benefit for games, so they are not in LeanFPS at all, not even behind an advanced switch.
The reasons for each are listed on the Windows gaming tweaks page.
- Microsoft Defender, Memory Integrity (HVCI) and virtualization-based security
- Windows Firewall rules and Windows Update services
- CPU security mitigations such as Spectre and Meltdown protections
- Game files, game memory, injected code or overlays
- Your documents, downloads or any personal files
- Registry cleaning, page file removal, CPU idle states
- Realtime process priority, which can freeze input and audio
What the risk labels mean
Low risk tweaks change a setting Windows itself exposes, take effect right away and are fully reversed by turning them off. Medium risk tweaks can have side effects on some systems: hardware-accelerated GPU scheduling and the multiplane overlay switch need a restart, and high priority for every game can make voice chat or a browser feel slow while you play. Medium-risk tweaks are never in the Recommended preset.
Where LeanFPS keeps its data
Settings, the undo journal and your FPS history are JSON files in C:\ProgramData\LeanFPS. Nothing is sent anywhere: the current version of the app makes no network requests. Opening the Pro page in your browser is the only time it hands anything to the internet, and that is your browser visiting our website.
Before you start
- Download LeanFPS only from this website.
- Start with the Recommended preset and play a few sessions.
- Use FPS measurement to check that a change helped before keeping it.
Have a question about a specific change? Every tweak in the app has an info panel with the exact setting it touches. You can also contact us. Back to the LeanFPS game optimizer.
Safe game optimizer FAQ
Is LeanFPS a safe game optimizer for a work or school PC?
LeanFPS needs administrator rights to change power plans and process priority, so use it only on a PC you are allowed to change. It does not touch security settings, but your organization may still have rules about installing tools.
What happens if LeanFPS crashes during a game?
Session tweaks are written to a journal before they are applied. The next time LeanFPS starts, it finds the unfinished session and reverses those tweaks before doing anything else.
How do I remove LeanFPS completely?
Press Restore all in the app, or run leanfps.exe --restore-all from a terminal, then delete leanfps.exe and the folder C:\ProgramData\LeanFPS. Restore all puts back every value LeanFPS changed.
Why does it ask for administrator rights?
Changing the power plan, process priority of other programs and some system-wide settings requires administrator rights in Windows. Windows asks for permission when LeanFPS starts. If you turn on start with Windows, a scheduled task starts it with those rights so you are not asked at every boot. LeanFPS does not install a driver or a service.
Can it break my game install or get me banned?
LeanFPS never writes to game folders or game memory and never draws an overlay, which are the things anti-cheat systems watch for. It only changes Windows settings and process priority from outside the game.
Try LeanFPS on your own games
Free to use with no account. The first three games you play get every Pro tweak, so you can compare your own FPS before you decide.