<<The problem with them is that they are not deleted when a program is uninstalled - Iíve tried the standard Windows Uninstaller and also different clean uninstallers like Revo, CleanseIn, Free Uninstall -none can delete .pf files and I have to remove them manually.>>
Well...I have about 100 of these files on my system...and I wonder why you are concerned with them?
In any case, take a look at Prefetch
I would take issue with the assertion that fooling around with these files is worth the effort. Of the 95 files I see listed, the majority are well less than 100kb in size. 100 MB of hard drive space...is pretty insignificant on a system like mine that has well over 500GB of occupied hard drive and several hundred thousand files.