Fullscreen optimizations and Game Mode: on or off?

First, the honest sentence. None of the three switches on this page raises a frame rate on its own: two of them decide how a game's frames reach the screen, and the third tells Windows that a game is in front. w0a has no measurement of what any of them changes on your machine, so this page shows exactly what each box writes, how to read it back, and how to measure it yourself.

They come up in the same sentence constantly — "turn off fullscreen optimizations and Game Mode" is one of the oldest lines in this field — and they are unrelated settings that do unrelated things. The advice is also a decade old, and Windows changed underneath it.

Here is what each one is, what changed, and how to answer the question for your machine rather than for someone else's.

What fullscreen optimizations actually is

When a game asks for exclusive fullscreen — the old mode where the game owns the display outright — Windows can instead run it as a borderless window that still presents directly to the screen. That is the "optimization": you keep the things exclusive fullscreen breaks (fast alt-tab, overlays, notifications, Auto HDR) and, when the conditions are met, you keep presentation going straight to the display without a stop at the desktop compositor.

The mechanism that makes that possible is called independent flip: the game's buffers are handed to the display directly, and the compositor stands aside. When the conditions are not met — an overlay in the way, a window that is not really fullscreen, a mismatched format — presentation falls back to composition, every frame gets a composition stop added to it, and each transition between the two lands as a hitch.

That fallback, not the setting, is what people are actually feeling when this helps them.

Why the old advice is dated

Windows 11 did not retire the legacy blit path. A DirectX 12 game always presents through the flip model, and the windowed-games setting further down can move an eligible DirectX 10 or 11 game off blit, but a windowed game neither covers still copies every frame the old way. The fullscreen-optimization values concern games that ask for exclusive fullscreen. w0a writes them on Windows 11 too, but whether Windows 11 still reads them was not measured — and w0a says exactly that in the message it prints when it writes the values, rather than letting you believe you just found a machine-wide gain.

There is a second thing worth knowing, because it is the source of endless confusion in guides that quote registry values at each other: a clean Windows install ships with the behaviour value already set to 2 and the "honour the user's choice" flag at 0. Fullscreen optimizations are on because that flag is 0, not because the other value is. Reading the first value alone tells you nothing, which is why a page telling you your machine "already has it disabled" is often reading it wrong.

When turning it off is a legitimate experiment

Not never. It is a reasonable thing to try when:

the game is an older DirectX title that genuinely wants exclusive fullscreen;
colour, gamma or HDR behaves oddly in one specific game;
an overlay or capture tool misbehaves only in that game.

Do it per game first — the checkbox on the executable's Compatibility tab — rather than machine-wide. One game's problem is not a reason to change how every game presents.

And know what you are giving up: alt-tab gets slower, Auto HDR does not apply to a game running in true exclusive fullscreen, and some overlays stop drawing. Those are the exact symptoms the fullscreen optimizations repair card exists to undo — it writes the Windows defaults back unconditionally, whichever tool changed them.

The other setting: optimizations for windowed games

Different switch, different Windows version, frequently confused with the one above. Windows 11 22H2 added a setting for windowed or borderless games: Microsoft says it moves a compatible DirectX 10 or 11 game from the older blit presentation to the flip model. That is Microsoft's description, not a gain w0a measured. Before 22H2 the value is not read at all.

Who it is for: by Microsoft's description, DirectX 10 and 11 games played windowed or borderless; whether it helps on your machine has not been measured.
Who it does nothing for: anyone on an older Windows build, and anyone already running exclusive fullscreen.
One interaction worth knowing: with Auto HDR on, Windows keeps the feature on by itself.

w0a can turn this one on, and the windowed game presentation card removes only the value w0a itself wrote — if you switched the feature off deliberately in Windows' graphics settings, that choice is left alone. Turning off a setting the user chose is not a repair.

Game Mode

What it does: tells Windows that a game is in the foreground, so it holds some background work back and stops driver installations and restart prompts from arriving mid-match.

Who it helps: a machine with background work that would otherwise land mid-match; how much it changes on yours has not been measured. It is worth leaving on.

Where the "turn it off" advice comes from: a small number of machines where someone measured a problem with it and wrote it up, after which the advice spread to everyone. That is a testable claim, not a rule — and if you test it, test it the way any other change should be tested, below.

What it is not: a frame-rate feature. If you are hoping for a number to move, this is not the setting that moves it.

What w0a writes, box by box

Three boxes touch this subject. Each one records the previous value before it writes, so undoing changes puts back what was there before. The repair cards named below do something different: they write Windows' defaults back, whichever tool changed the values.

"Disable fullscreen optimizations (FSE)" (Optimizations page)

Four values, all DWORD, under HKEY_CURRENT_USER\System\GameConfigStore:

Value	The box writes	Windows default (what the repair card writes back)
`GameDVR_FSEBehaviorMode`	2	2
`GameDVR_HonorUserFSEBehaviorMode`	1	0
`GameDVR_DXGIHonorFSEWindowsCompatible`	1	0
`GameDVR_EFSEFeatureFlags`	0	not present

The first row is the same on both sides, so what the box actually changes are the other three values.

When it applies: w0a asks for no restart for this box. Microsoft does not say whether a game that is already running picks the change up, so close the game and start it again before you judge anything.
On Windows 11: w0a writes the four values on build 22000 and later as well; whether Windows 11 still reads them was not measured, and the message it prints there says exactly that.
Every game, not one: the box changes this setting for every game this Windows user runs. The per-game route is the one Microsoft documents: right-click the game's executable, Properties, the Compatibility tab, tick Disable fullscreen optimizations, Apply. w0a has no box that sets that per-game checkbox, so it stays your choice.
Way back: the fullscreen optimizations repair card writes the right-hand column back.

"Enable Windows Game Mode" (Optimizations page)

Two values, DWORD 1, under HKEY_CURRENT_USER\Software\Microsoft\GameBar: AutoGameModeEnabled and AllowAutoGameMode.

The box reads first. If both values already say 1, it writes nothing and tells you so; it does not report a change it did not make.
On a Windows older than Windows 10 version 1703 (build 15063) it writes nothing at all: Game Mode arrived in 1703, and on older builds the values would be read by nothing.
Windows default: when the values are absent, Windows applies its own default. Microsoft states that default only in a support answer, not in any policy or settings reference, so w0a's message does not name it and neither does this page.
When it applies: w0a asks for no restart for this box.
Way back: no repair card resets these two values. Undoing changes restores what was there before the box ran.

"Enable optimizations for windowed games (Windows 11 only)" (Game Optimization page)

One pair, SwapEffectUpgradeEnable=1, merged into the text value DirectXUserGlobalSettings under HKEY_CURRENT_USER\SOFTWARE\Microsoft\DirectX\UserGpuPreferences.

Merged, not overwritten: the same text also carries your Auto HDR, variable refresh rate and default GPU choices, and the box keeps them. If it cannot read the current text, it writes nothing and says so.
Windows version: before Windows 11 version 22H2 (build 22621) the box writes nothing and says the setting does not apply.
What Microsoft says it covers: DirectX 10 and DirectX 11 games running windowed or borderless windowed. Microsoft describes it as moving compatible games from the older blt-model presentation to flip-model, with lower latency; that is Microsoft's description, not a measurement taken on your machine.
Windows' own switch: Settings > System > Display > Graphics, and under Default settings the Optimizations for windowed games switch. For one game: Custom options for apps, the game, Options. Microsoft's page does not say whether the switch starts on or off.
Auto HDR: turning Auto HDR on turns this feature on automatically, and to turn this feature off you have to turn Auto HDR off first.
When it applies: Microsoft's instruction is to restart the game.
Way back: the windowed game presentation card removes only SwapEffectUpgradeEnable=1 from the global text. A SwapEffectUpgradeEnable=0 that you set, and any per-game entries, stay as they are.
What the stutter scan does with it: it mentions this setting only when the global text says SwapEffectUpgradeEnable=0 outright, as information and with no repair card, because that value is somebody's deliberate choice.

Check it yourself

These commands only read. Run them in Command Prompt or PowerShell:

reg query "HKCU\System\GameConfigStore"
reg query "HKCU\Software\Microsoft\GameBar" /v AutoGameModeEnabled
reg query "HKCU\Software\Microsoft\GameBar" /v AllowAutoGameMode
reg query "HKCU\SOFTWARE\Microsoft\DirectX\UserGpuPreferences" /v DirectXUserGlobalSettings

How to read the answers:

DWORD values are printed in hexadecimal. A line such as GameDVR_FSEBehaviorMode REG_DWORD 0x2 means 2; 0x1 means 1 and 0x0 means 0.
The first command lists every value under the key. Compare the four names with the table above; GameDVR_EFSEFeatureFlags missing from the list is the Windows default.
When a value you asked for by name does not exist, reg query ends with an error instead of printing a line. For the two Game Mode values that means "not set", and Windows' own default applies.
The last command prints one line of Name=Value; pairs. SwapEffectUpgradeEnable=1 means the feature was switched on, by the box or by the Settings switch; SwapEffectUpgradeEnable=0 means somebody switched it off on purpose; no such pair means nothing set it for every game.

How to actually decide

The counter will not answer this question for you: both settings change how frames reach the screen, which shows up in pacing and in the tail, not in the average.

Pick one game and one repeatable scene.
Capture the unchanged configuration three times, so you know your own run-to-run noise. Reading the benchmark covers why that step is not optional.
Change one of the two settings.
Capture the same scene the same way, and compare the 1% lows — not the average. High average FPS but bad 1% lows explains what you are reading.
Undo anything that did not move a number past your own noise.

There is one more number worth watching here specifically. A saved capture records when presentation fell back to composition, and the stutter scan reports it as a finding of its own with the count. If that number is high, the useful question is not "FSO on or off" but "what is forcing composition" — usually an overlay, or a window that is not the size the display is.

What is not on this page

Disabling the desktop compositor, the MPO registry values and the TDR values all circulate in the same guides as this subject. w0a refuses to write them, and for the registry values the reasons are on record:

OverlayTestMode and DisableOverlays switch off multi-plane overlay. On a real Windows 11 25H2 machine they froze CS2 hard and repeatably: the whole computer, not only the game.
TdrDelay and TdrDdiDelay lengthen the graphics-driver watchdog, which only makes each freeze last longer; TdrLevel switches recovery off altogether.
EnablePreemption is a driver-model debug value with no measured frame benefit, and it takes away the GPU's ability to recover from a hung workload.

w0a also does not set the per-game Compatibility checkbox and has no box that turns Game Mode off. If a previous tool set any of the registry values above, display and video and GPU crash recovery put the Windows defaults back.

Which Windows settings change anything in a game, who each one helps and who it does nothing for: How to optimize Windows 11 for gaming: the settings that actually matter

w0a changes no Windows setting until you ask it to, and before a tweak writes a new value it saves the old one. Get notified

Did this page help?

What was missing, or what did not work? We read every one of these.

If this page did not solve it, write to us — say which article you read, and we will fix the article.