Compress WinSxS Folder

1. Query service status. Track its state.

sc query msiserver
sc query TrustedInstaller

2. Stop/disable Windows Installer and Windows Module Installer services

sc stop msiserver
sc config msiserver start= disabled
sc stop TrustedInstaller
sc config TrustedInstaller start= disabled

3. Backup ACLs for WinSxS folder.

icacls "%WINDIR%\WinSxS" /save "%WINDIR%\WinSxS.acl" /t

4. Take ownership of WinSxS folder

takeown /f "%WINDIR%\WinSxS" /r

5. Grant full rights on WinSxS to user

icacls "%WINDIR%\WinSxS" /grant "USERNAME7":(F) /t

6. Compress Folders

compact /s:"%WINDIR%\WinSxS" /c /a /i *

7. Restore ownership

icacls "%WINDIR%\WinSxS" /setowner "NT SERVICE\TrustedInstaller" /t

8. Restore ACLs

icacls "%WINDIR%" /restore "%WINDIR%\WinSxS.acl"
del "%WINDIR%\WinSxS.acl"

9. Restore services, replace "demand" and "start" with the right state

sc config msiserver start= auto
sc start msiserver
sc config TrustedInstaller start= auto
sc start TrustedInstaller

From http://blog.aslanbrooke.com/2015/07/25/compressing-winsxs-and-installer-on-windows.html