While Working on system some temporary files are created with extension.pf, it will cause your system slow. to disable the function follow the steps(Disable the Prefetch data collection)
Open Registry Editor.
Navigate to the following Registry Values.HKEY_LOCAL_MACHINE –> System –>Current ControlSet –> Control –>SessionManager –> Memory Management –> PrefetchParameter
Look for the word Enable Prefetcher in the Right Pane and Set the value to 0.
Start –> Run
Type prefetch and press Enter.
Delete all the files.
Editing the Registry will cause the System unstable. Please take a Proper Back-Up before editing with Registries.