Exclude paths from Windows 7 backup

 https://kb.synology.com/en-id/C2/tutorial/How_do_I_exclude_files_and_folders_from_backups
 https://learn.microsoft.com/en-us/windows/win32/vss/excluding-files-from-shadow-copies

To exclude files / folders / paths from Windows 7 backup:

1) In Regedit.exe, navigate to the following regkey.
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\BackupRestore\FilesNotToSnapshot
2) Create a new MULTI_SZ regval called anything descriptive, or such as, "Excluded-20240121".
3) Double-click the new regval to open it, and add the full file path of the file name, folder name, or wildcard you want excluded.
4) Add multiple paths to the regval, or repeat with additional regvals as necessary.

This regkey should already exist and contain default values for various commercial products, and you can see these as examples.  There are features to support subdirectories, wildcards, and also some stock variables.

Exclude all files in C:\temp, but not subfolders:
  C:\temp\*.*

Exclude all WSUS downloaded files with subfolders:
  %windir%\softwaredistribution\*.* /s

Exclude all Firefox browser cached files stored in all user profiles:
  $UserProfiles$\AppData\Local\Mozilla\Firefox\Profiles\tofolsma.default-esr\cache2\*.*

Exclude all enumerated NTLite temp folders and their subfolders
  C:\NTLite.tmp\Temp\NLTmp* /s

Exclude Temp folder from each drive with subfolders
 $AllVolumes$\Temp\*.* /s

Exclude all Windows upgrade files left behind on all volumes:
  $AllVolumes$\$WINDOWS.~BT\*.* /s