Built-in FPS and 1% low measurement
Each session is compared with your earlier sessions of the same game. No overlay, nothing injected into the game.
How we measure FPSWindows 10 and 11 · 5.9 MB download · free
The game optimizer that shows you the numbers
LeanFPS is a lightweight game optimizer for Windows. It recognizes the game you launch, applies tweaks made for that kind of game, measures your FPS and 1% lows, and puts every setting back when you stop playing.
- No account to start
- Every change can be undone
- Never weakens Windows security
LeanFPSPro trial · 2 games leftOptimizing nowCounter-Strike 2Competitive shooter ▾
241FPS now
236Average
1681% low
6 optimizations active2 for competitive shooter
- Raw aim: mouse acceleration off
- High priority for competitive play
- ▸ 4 general optimizations
Tip Turn on NVIDIA Reflex or AMD Anti-Lag in the game’s graphics settings.
Restore allUnlock Pro · $19 early-bird
6.5 MBInstalled size. One exe, no .NET, no WebView, no wallpapers.
16Tweaks, each with what it changes and why
68Games and emulators in the built-in list, plus Steam and Epic libraries
0Security settings touched
Try it
See which stutter each tweak removes
Two sessions can have the same average FPS and feel completely different, because stutter lives in the slowest frames. Each colored spike below has a cause. Switch on the game optimizer tweak for it and watch the 1% low climb.
Average FPS135
1% low51
Stutter spikes22
Simulated16.7 ms · 60 FPS6.9 ms · 144 FPS
Simulated frame times, one bar per frame. Taller bars are slower frames you feel as stutter. Not a benchmark: what you gain depends on what slows your PC down, and LeanFPS measures your real numbers.
Turn on a tweak to remove the stutter it causes
Simulated frame times. Not a benchmark: what you gain depends on your PC, and LeanFPS measures your real numbers.
Feel it
Same flick, different aim: mouse acceleration in a game
Windows turns on mouse acceleration (Enhance pointer precision) by default. With it, how far you turn depends on how fast you move, so a slow flick stops short and a fast one overshoots. Both views below get exactly the same hand movement. Press a flick, or drag on the game view and tap to shoot.
Or drag on the game view to aim, tap to shoot
Illustration with an exaggerated acceleration curve. Most shooters read raw mouse input already; LeanFPS turns acceleration off for the ones that do not, and for menus, while you play.
How it works
How the LeanFPS game optimizer works
Most game optimizer apps run a long list of registry edits once and ask you to trust the result. LeanFPS works per game and per session, and it records what it did.
Detect the game
Every 2 seconds LeanFPS looks at the foreground window. It matches the game against its built-in list, your Steam, Epic, GOG, Battle.net and Ubisoft libraries, or a fullscreen check, and shows the game with its icon and genre.
Apply the right tweaks
A shooter gets raw mouse input and high priority. An open-world game gets standby-memory cleanup. A laptop keeps its power plan and switches to Best performance mode only while you play.
Measure, then restore
While you play, LeanFPS counts frames from Windows event tracing and saves your average FPS and 1% low. When the game closes, session tweaks are reversed in the opposite order.
Key optimizations
What the most important tweaks actually change
Every tweak in this game optimizer fixes one specific thing Windows does while you play. Pick one and compare before and after.
High performance power plan
Balanced plan: the CPU drops to power-saving clocks between frames and needs time to ramp back up. Frames that start during the ramp take longer.
Details and sourcesIllustration of how the setting works, not a measurement.
Why LeanFPS
A game optimizer built to be trusted
Gamers are right to be suspicious of FPS boosters. These are the things we built so you do not have to take our word for anything.
Game profiles by genre
Eight genres with their own tweaks and tips, from competitive shooters to MMOs and emulators.
See game profilesReal undo, one tweak at a time
The real previous value is saved before every change and restored on undo, even after a crash.
Safety and undoSmall and quiet
About 6.5 MB on disk. With the window closed it checks the foreground window every 2 seconds and stays near 10 MB of memory.
Laptop aware
On laptops LeanFPS never swaps your power plan. It uses Best performance mode and the dedicated GPU only while a game runs.
No placebo, no risky switches
No timer-resolution tricks that stopped working in Windows 10 2004, no registry cleaners, no Defender or HVCI changes.
What it changes
What this game optimizer does, and what it never does
Every tweak in LeanFPS has a written reason and a way back. Settings that lower your security, or that do nothing measurable, are not in the list at all.
- Power plan and core parking on desktops
- Game Mode on, background recording off
- Game priority and no power throttling while playing
- Background apps lowered, restored after
- Mouse acceleration off for shooters
- Standby memory cleanup for open worlds
Never changed
- Microsoft Defender and Memory Integrity (HVCI/VBS)
- Firewall rules and Windows Update
- CPU security mitigations
- Game files, game memory, overlays
- Registry "cleaning" and page file removal
Undo
Every change goes back when you stop playing
Drag through one gaming session. LeanFPS writes down the real previous value before each change and puts it back in reverse order 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.
Compared
LeanFPS next to every popular game optimizer
Seven other ways to tune Windows for games, from Radiant Optimizer and Hone to the Game Mode already in Windows. Every competitor fact comes from the maker's own site or download, read on 2026-10-10. Sources are on the full game optimizer comparison.
| Compared 8 ways to optimize Windows for games | LeanFPSGame optimizer | Radiant OptimizerGame optimizer | HoneFPS booster (Overwolf) | Razer CortexGame booster | Tier1SuiteTweak suite | Process LassoProcess manager | WinUtilOpen-source script | Windows Game ModeBuilt into Windows |
|---|---|---|---|---|---|---|---|---|
| Price | ||||||||
| Free version | Yes. Detection, FPS measurement, core tweaks; no time limit | Yes. 8 starter tweaks; profiles only as a preview | Partly. 10 optimizations (15 with referrals), with ads | Yes. No paid tier shown | Yes. 20 of 43 catalog entries | Yes. Free edition | Yes. Free, MIT license | Yes. Built in |
| Full version priceOne PC, US prices | Yes. $19 once (early-bird; $29 later) | Partly. $57.77 once | No. $5.99 a month or $39.99 a year | Yes. Free | Partly. $29.99 once (3 PCs) | Partly. $39.95 lifetime, or $24.95 a year | Yes. Free | Yes. Free |
| Size and footprint | ||||||||
| Download size | Yes. 5.9 MB installer, about 6.5 MB installed | No. 194 MB installer (v7.0.4) | Partly. 3 MB Overwolf stub, downloads more | Partly. 15 MB web installer, downloads more | No. 75 MB installer | Yes. 3 MB installer | Yes. 0.9 MB PowerShell script | Yes. Nothing to install |
| No account needed | Yes. No account, free or Pro; Pro works with a key and email. Signing in is optional | Partly. Free: no. Premium: account and motherboard-locked licence | No. “Do I need to sign in? Yes.” | Not stated. Not stated | Yes. No account | Yes. Pro needs an activation code | Yes. No account; run as administrator | Yes. No account |
| Proof it works | ||||||||
| Measures your real FPS | Yes. Every session, from Windows event tracing; no overlay | Partly. Premium “Live FPS overlay”, method not stated; home page demo is simulated | Not stated. Not stated | Partly. FPS counter; Booster Prime gives a predicted FPS | Partly. Latency benchmark; per-game frame time “not measured” | No. No FPS measurement stated | No. None | Not stated. Not stated |
| 1% lows saved per sessionTo see whether a tweak really helped | Yes. Average, 1% and 0.1% lows, compared with your usual | Not stated. Not stated | Not stated. Not stated | Not stated. Not stated | No. Not measured | No. | No. | Not stated. Not stated |
| Safety | ||||||||
| Never weakens securityDefender, Memory Integrity, Windows Update, firewall, mitigations | Yes. None of these are in the tweak list | Not stated. Not stated | Not stated. Not stated | Not stated. Not stated | Partly. Offers turning off VBS / Memory Integrity (opt-in, Pro) | Not stated. Not stated | Partly. Optional “Disable Updates” stops security updates | Yes. Only holds back driver installs and restart prompts |
| Undo one change at a time | Yes. Real previous value saved before each change | Partly. “Supported settings” have backup or undo | Partly. Supported registry tweaks | Partly. Restores after gaming; Booster Prime has Revert | Yes. Per-tweak revert and revert all | Yes. No changes left after uninstall | Yes. “Undo Selected Tweaks” | Yes. One switch |
| Privacy and support | ||||||||
| Sends nothing from your PC | Yes. Free: no network requests. Pro: only license activation and a weekly renewal | No. Registered users “cannot opt out” of usage data | No. May collect hardware, BIOS settings, installed games | Not stated. Not stated | Partly. Update check; usage data only if you opt in | Yes. Only activation and update checks | Not stated. Not stated | Not stated. Not stated |
9 rows shown. Scroll sideways to see every product.
Pricing
Free game optimizer, Pro for $19 once (early-bird)
The free version includes game detection, FPS measurement and the 5 core tweaks. Pro adds the game-time and per-genre tweaks. Your first three games run with everything on.
Game optimizer FAQ
Does a game optimizer actually increase FPS?
Sometimes, and usually by a few percent rather than a lot. The biggest FPS gains still come from in-game settings and upscaling. What a game optimizer can fix is the PC getting in the way: power saving between frames, background apps taking CPU time, Windows moving the game to efficiency cores. LeanFPS measures your average FPS and 1% lows each session so you can see whether it helped on your PC.
Is LeanFPS safe for VALORANT, CS2 and other anti-cheat games?
LeanFPS never injects into a game, never reads or writes game memory or files, and shows no overlay. It changes Windows settings and process priority from outside the game. When an anti-cheat blocks priority changes on the running game, LeanFPS uses the Windows launch priority setting instead, which applies the next time the game starts.
Can I undo everything?
Yes. Before each change LeanFPS saves the real previous value, not a guessed Windows default. You can turn off any tweak on its own, press Restore all, or run leanfps.exe --restore-all. Changes made only while a game runs are undone when the game exits, and after a crash they are undone the next time LeanFPS starts.
Does it turn off Defender, the firewall or Windows Update?
No. LeanFPS never touches Microsoft Defender, Memory Integrity (HVCI/VBS), the firewall, Windows Update or CPU security mitigations. Those trade your safety for little or no gaming benefit.
How much does LeanFPS cost?
The free version detects games, measures FPS and applies the core system tweaks. Pro is a one-time payment of $19 at the early-bird price ($29 later), with no subscription and unlocks the game-time and per-genre tweaks. Your first three games get every Pro tweak for free.
Does it stay running in the background?
Only if you want game detection. With the window closed, LeanFPS checks the foreground window every 2 seconds and stays around 10 MB of memory on our Windows test runner. You can also quit it after applying the system tweaks.
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.