Thursday, March 27, 2008

28. Alter Prefetch Parameters

Pre-fetching (the reading of system boot files into a cache for faster loading) is a
commonly overlooked component that can have a significant impact on system boot
time.
To see which files are gathered using each setting, clear the prefetch cache
located at C:\Windows\Prefetch and then enable one of the settings listed in this hack.

Clear the cache and repeat for each setting. Set the Registry key
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\
Memory Management\PrefetchParameters\EnablePrefetcher to 0 to disable
prefetching, 1 to prefetch application launch files, 2 to prefetch boot files, or 3 to prefetch as many files as possible.

1 Comment:

Anonymous said...

Yet another confused and inaccurate prefetch article.

Prefetch is not a cache. Prefetch files are used by Windows to optimize both boot and application launch times. Application prefetch files are referenced only when the program is started, not at boot time. Unused or rarely used entries will have virtually no impact on performance. In any event the folder is self cleaning after 128 entries. Manual cleaning will temporarily impair performance and has no benefits.

The default and optimum setting for EnablePrefetcher is 3. There is nothing to be gained by setting it to any other value.

References:
http://home.comcast.net/~SupportCD/XPMyths.html

Larry Miller
Microsoft MCSA