3 Application Compatibility Registry Tweaks to Boost Windows Vista and Windows 7 Performance

You all are aware of our "Master Tutorial" series which helps you in making your Windows faster:

And today in this tutorial, we are going to share 3 more registry tweaks which will help you in improving your system performance.

We all know about "Application Compatibility" feature of Windows Vista and Windows 7. It helps you in running old software programs which are not compatible with new Windows versions. It monitors your system and whenever you run a program, it looks through a compatibility database. If it finds a match for the running application, it offers you the solution or compatibility fixes. If a match is not found, it shows a message that the application has a known problem with current Windows version.

Application compatibility feature comes with 3 main components:

  • Application Compatibility Engine
  • Program Compatibility Assistant
  • SwitchBack Compatibility Engine

Application Compatibility Engine is the main part of the system loader and performs the check through program compatibility database.

Program Compatibility Assistant (PCA) monitors user initiated programs for known compatibility issues at run time and provides recommended solutions to the user.

SwitchBack Compatibility Engine provides older system behavior to older applications and new system behavior to new applications.

All these 3 components are enabled by default in Windows Vista and Windows 7. Turning off these features will boost your system performance. However it may degrade the compatibility of older applications and may not block known incompatible applications from installing. Also you'll not receive solutions to known compatibility issues when running applications.

Turning off "Application Compatibility" feature is useful for people who like faster systems and want to achieve maximum performance from their systems and are aware of compatibility of the applications they are using.

So if you want to make your Windows faster and don't care about application compatibility, you can follow these instructions to turn application compatibility feature off:

1. Type regedit in RUN or Start Menu search box and press Enter. It'll open Registry Editor.

2. Now go to following key:


3. Create a new key AppCompat under Windows key.

4. Select new AppCompat key and in right-side pane, create following 3 new DWORD values:

  • DisableEngine
  • DisablePCA
  • SbEnable

5. Set values of DisableEngine and DisablePCA to 1 and value of SbEnable to 0


6. If you are using 64-bit Windows edition, you'll also need to follow the same steps 3-5 for following key:


7. That's it. Close Registry Editor and restart your system to take effect.

Now you should notice faster system performance but you'll be unable to enjoy application compatibility feature.

PS: If you want to restore default settings and want to enable application compatibility feature, just remove the 3 DWORD values created in step 4.

NOTE: If you don't want to modify Registry manually and want a ready-made Registry script to do the task automatically, download following ZIP file, extract it and run the extracted REG file. It'll ask for confirmation, accept it:

Download Registry Script

Feel free to share your feedback in your comment. Do you use application compatibility feature in Windows?

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Posted in: Windows 7, Windows Vista

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  • Thank You VG,
    Is there any Disadvantage to PC.?

  • VG

    ^^ No. Except no access to compatibility mode. If you dont run applications in compatibility mode, you can increase system performance by disabling it.

  • Will this affect older apps (or games) that don't use compatibility mode? Midtown Madness 2 runs great and is my favorite.

  • So by runs faster you mean it just launches the application faster?

  • VG

    ^^ Launching will be definitely faster, also you should notice a little bit improvement in overall system performance because the application compatibility feature will not regularly monitor running programs, etc.

    No. If a program is not using compatibility mode, it'll not be affected.

  • With my 64-bit, it will not allow me to make another key named "AppCompat". It states there's already a key with the same name. Is there a workaround for this?

    Also I was wondering, with 64-bit, you don't have to create any QWORDS? Only DWORDS. Thank you!

  • VG

    ^^ If the key already exists, you dont need to recreate it. Simply create the mentioned DWORD values in right-side pane.

  • Can we also "Disable Application Compatibility Feature in Windows 7"
    by stopping or disable some services ?

  • VG

    ^^ You can set "Program Compatibility Assistant Service" to Manual but it would be a partial solution. The perfect solution would be using the above mentioned registry tweaks.

  • Nice update idd VG! Really nice imo.
    Just keep that :)

  • Good idea, VG. If I'd like to have the ability to manually set and use compatibility via the executable's properties, but would definitely like to disable the monitoring aspect, which of these settings should I use?

  • Nice tweak VG
    Applied and working.....

  • Very Nice post sir my computer startup items opened within 2sec..Amazing..thanx

  • HI

    I've test this "tweak" today, almost OK, why almost?
    S.I.W 2011 (latest free version) stop working properly after this reg. tweak, generally SIW can't read sensors from mobo, never ending scan and program hangs, You can close window but SIW process is still present in task manager, after tweak reverse works OK again, just informative, SIW don't use compatibility option, it is native Windows 7 program (also), so this reg. tweak isn't for me :)

  • I'd just like to inform you that this tweak can cause some problems with "Defraggler", an application made by Piriform, the makers of CCleaner. With this tweak applied, one can experience problems in performing "Boot Time Defrag" under Defraggler.

  • These tweaks make some app like CPUZ, Speecy, SpeedFan and HWMonitor don't run anymore. (I don't use compatibility mode on these apps.)

  • hmm nice article VG but why can't i see the AppCompat under the Windows key? i'm using 64-bit version of windows 7..

  • VG

    ^^ You'll need to create it manually.

  • There seems to be a problem running iTunes with this tweak, getting iTunes to detect an iDevice or remain stable for a reasonable period of time is impossible. I removed the tweak and lo and behold, it works again.

  • I too was having trouble with iTunes and Dropbox syncing.

    With these tweaks applied these sync services will not automatically happen.

    Once the tweaks were removed everything is syncing properly.

  • please make a tutorial no how to speed up windows 8. :D

  • When I try to rename the key "new key #1" in "HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Policies\Microsoft\Windows\", it gives me an error:

    [Window Title]
    Error Renaming Key

    The Registry Editor cannot rename New Key #1. The specified key name already exists. Type another name and try again.


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