What is the standard value of SystemResponsiveness?

Frozen Tweaks writes 20 when you switch the tweak off, which is the value it treats as the Windows standard. With the tweak on, SystemResponsiveness is 10.

Is "Tune MMCSS for Games" safe to switch on?

Low risk and reversible. Expect a difference only when the processor is contested, not an FPS number. The main cost: Background work (downloads, recording, a browser) gets less processor time while a game runs.

Switch the tweak off in Frozen Tweaks. Switching it off writes the game scheduling values Windows ships with.

Is "Tune MMCSS for Games" free in Frozen Tweaks?

It is part of Frozen Pro and Elite. You can also make the change by hand with the values on this page.

SystemResponsiveness and the MMCSS Games task: values, defaults and what they do

Frost LIVECPUProUndo: YesUpdated Oct 8, 2026View as Markdown

Short answer

Updated Oct 8, 2026

MMCSS is the Windows service that gives audio, video and game threads priority. SystemResponsiveness is the share of processor time it keeps back for everything else, and the Games task holds the priority a game thread gets when it asks. This tweak lowers the reserve and raises the Games task values. In the registry it sets SystemResponsiveness to 10 under HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Multimedia\SystemProfile, and 5 more values.

In the app

Tune MMCSS for GamesPRO

Registry

HKLMSOFTWARE\Microsoft\Windows NT\CurrentVersion\Multimedia\SystemProfile

SystemResponsiveness2010

What the switch writes. Your current value may differ. 5 more changes below.

What it does

In the app the switch is called "Tune MMCSS for Games", described there as: Reduces SystemResponsiveness and boosts game task priority to cut scheduling jitter.

When it helps, and when it hurts

When it helps

Games and audio that register with MMCSS, on a PC that is busy with other work at the same time.

When it hurts

Background work (downloads, recording, a browser) gets less processor time while a game runs.
Many games never register with MMCSS, and for them the Games task values change nothing.

What it writes

Exactly what the switch changes, read from the app's source. Switching it off is what the app writes when you turn the tweak off again.

Registry values the switch writes.
Key and value	With the tweak	Switching it off
HKLMSOFTWARE\Microsoft\Windows NT\CurrentVersion\Multimedia\SystemProfileSystemResponsiveness	10	20
HKLMSOFTWARE\Microsoft\Windows NT\CurrentVersion\Multimedia\SystemProfile\Tasks\GamesScheduling Category	High	Medium
HKLMSOFTWARE\Microsoft\Windows NT\CurrentVersion\Multimedia\SystemProfile\Tasks\GamesSFIO Priority	High	Normal
HKLMSOFTWARE\Microsoft\Windows NT\CurrentVersion\Multimedia\SystemProfile\Tasks\GamesGPU Priority	8	8
HKLMSOFTWARE\Microsoft\Windows NT\CurrentVersion\Multimedia\SystemProfile\Tasks\GamesPriority	6	2
HKLMSOFTWARE\Microsoft\Windows NT\CurrentVersion\Multimedia\SystemProfile\Tasks\GamesAffinity	0	0

From the app's source (tweaks_mmcss.hpp), app 2.0.0, checked Oct 8, 2026.

The same change by hand

You do not need the app for this one. These commands make the changes from the table above. Run them in a Command Prompt opened as administrator, and make a restore point first.

Make the change · CMD

reg add "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Multimedia\SystemProfile" /v "SystemResponsiveness" /t REG_DWORD /d 10 /f
reg add "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Multimedia\SystemProfile\Tasks\Games" /v "Scheduling Category" /t REG_SZ /d "High" /f
reg add "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Multimedia\SystemProfile\Tasks\Games" /v "SFIO Priority" /t REG_SZ /d "High" /f
reg add "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Multimedia\SystemProfile\Tasks\Games" /v "GPU Priority" /t REG_DWORD /d 8 /f
reg add "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Multimedia\SystemProfile\Tasks\Games" /v "Priority" /t REG_DWORD /d 6 /f
reg add "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Multimedia\SystemProfile\Tasks\Games" /v "Affinity" /t REG_DWORD /d 0 /f

Put it back · CMD

reg add "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Multimedia\SystemProfile" /v "SystemResponsiveness" /t REG_DWORD /d 20 /f
reg add "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Multimedia\SystemProfile\Tasks\Games" /v "Scheduling Category" /t REG_SZ /d "Medium" /f
reg add "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Multimedia\SystemProfile\Tasks\Games" /v "SFIO Priority" /t REG_SZ /d "Normal" /f
reg add "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Multimedia\SystemProfile\Tasks\Games" /v "GPU Priority" /t REG_DWORD /d 8 /f
reg add "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Multimedia\SystemProfile\Tasks\Games" /v "Priority" /t REG_DWORD /d 2 /f
reg add "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Multimedia\SystemProfile\Tasks\Games" /v "Affinity" /t REG_DWORD /d 0 /f

See what it is set to now · CMD

reg query "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Multimedia\SystemProfile" /v "SystemResponsiveness"

How to undo it

In the app: Yes

Switching it off writes the game scheduling values Windows ships with.

Switch the tweak off in Frozen Tweaks. It writes SystemResponsiveness back to 20, Scheduling Category back to Medium, SFIO Priority back to Normal and the other values in the table.

Changing several settings at once? The app's Make a restore point button, on every plan, makes a Windows restore point before you start.

Verdict

Low risk and reversible. Expect a difference only when the processor is contested, not an FPS number.

Questions

What does the "Tune MMCSS for Games" tweak change in Windows?: In the registry it sets SystemResponsiveness to 10 under HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Multimedia\SystemProfile, and 5 more values. The full list is in the table on this page, read from the app's source.
What is the standard value of SystemResponsiveness?: Frozen Tweaks writes 20 when you switch the tweak off, which is the value it treats as the Windows standard. With the tweak on, SystemResponsiveness is 10.
Is "Tune MMCSS for Games" safe to switch on?: Low risk and reversible. Expect a difference only when the processor is contested, not an FPS number. The main cost: Background work (downloads, recording, a browser) gets less processor time while a game runs.
How do I undo it?: Switch the tweak off in Frozen Tweaks. Switching it off writes the game scheduling values Windows ships with.
Is "Tune MMCSS for Games" free in Frozen Tweaks?: It is part of Frozen Pro and Elite. You can also make the change by hand with the values on this page.

In the app