I have a dll cache folder of 474MB in \system32 and one of 88MB in
\LastGood\System 32. Also a much smaller Prefetch folder. Can I safely
delete the contents of these? Will these fill up again if I do and what are
the advantages or otherwise of doing so?
The dllcache folder is the backup source used by Windows File Protection
(WFP) . If using NTFS, the files are compressed to take up less room
(compare total size to size on disk to see the difference). If you remove
the files, WFP will prompt you for the Windows installation files whenever
a system file is damaged or inappropriately changed (wrong version).
"Last Known Good" is a safety net. It stores the configuration from the
last successful boot. If your system can't boot one day for whatever
reason, booting to the Advanced Start Menu and selecting "Last Known Good"
will cause those files to be used to boot the system.
Prefetch is very small. It is a record about the usage patterns of
installed program files. Windows XP uses this information for optimizing
file placement when you run defrag and when the automatic background
maintenance occurs.
If pressed for room, dllcache is the only one I would consider removing and
only if the XP setup CD was handy at all times. This CD should have the
standard setup files on it. Not all OEM CDs store those files in a manner
that will work with WFP. Since I prefer not to be bugged by prompts and
have enough space, I leave the folder alone.
