Registry settings (continued)
PagingFiles. This option specifies the location, file name and size of the Page File(s) for the system, for example; c:\pagefile.sys 1024 2048
Note - This is the similar to the Virtual Memory options window, accessible in the Performance Options, Advanced tab, pressing the Change button: although it does allow you to potentially rename the Page File if that is of use.
SecondLevelDataCache. This setting specifies the L2 Cache size of your CPU (Defaulting to 256K when unable to determine) and it's only appropriate to specify a value with CPUs with off-die L2 Cache (i.e. Pre-Pentium 2; in which case - update your hardware!).
With any remotely modern CPU Windows accurately queries this value via the Hardware Abstraction Layer and as such there's no need to adjust this option. While some suggest you may set this manually regardless; it's completely unnecessary. Leave this set to 0. Other options listed, e.g. NonPagedPoolSize, can be ignored and are likely at their default of 0; indicating they are calculated automatically based on system configuration, e.g. RAM installed. Regardless, there's no need to modify these yourself.
Now navigate to the PrefetchParameters subfolder ([HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management\PrefetchParameters]).
Prefetching has been greatly enhanced in Vista, as such I'd recommend ensuring that EnablePrefetcher and EnableSuperfetch reset to their default values of 3 in the event they had been modified. Additionally there is no need to periodically clear the Prefetch directory (It clears unneeded entries itself), while using the /Prefetch command for launching Applications has no beneficial effect either.
Now navigate to [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer].
There may be a sub-key listed in the left hand pane entitled AlwaysUnloadDLL, with (Default) set to 1 in the right hand pane. Some recommend setting this as it frees unused DLLs (Dynamic Link Library) from memory quicker. This actually only applies to Windows Explorer extensions as Microsoft explains:
The Shell automatically unloads a DLL when its usage count is zero, but only after the DLL has not been used for a period of time. This inactive period might be unacceptably long at times, especially when a Shell extension DLL is being debugged. For operating systems prior to Windows 2000, you can shorten the inactive period by adding the following information to the registry.
Essentially, if you've got this sub-key listed right click on it (AlwaysUnloadDLL) and Delete it; it's completely unnecessary. Restart your system for changes to take effect.