Pf File Extension
Pf extension is associated with Prefetch pre-information file. You can try to open pf files with Windows XP system.
Generally, these are the system files which found in "C:\WINDOWS\Prefetch" folder. For every software there is different pf file in this folder. Windows xp checks this folder first before running any software, and it can run faster the software by using pf file.
You don`t have to make any changes on these files, Windows only uses these for speed.
What needed to Open Pf file extensions.
Windows XP is ended then you can try windows 10
Links about Pf file extension