In Windows Vista and Windows 7, the Prefetch function has been partnered with Superfetch: Vista uses a complex algorhytm to determine which applications are used and their access frequency, in order to preload parts of them into memory at Windows startup or at a later moment (determined by the algorhytm I was talking about). Since they are already partially loaded in memory, applications will startup faster than they did thanks to the traditional Prefetch.

Prefetch and Superfetch are theorically good functions. But pratically, things are a bit different. Prefetch does its work well, without any particular cons. Superfetch, instead, could lead to abnormal hard disk activity (caused by memory IO operations) and random in-game framerate drops (probably caused by the caching process). Moreover, Superfetch will use a considerable amount of system memory (even if it's managed with an accurate priority system), so tweaking this function might increase the overall performance of systems with less than 2 GiB of RAM. Fortunately Superfetch has been tamed down in Windows 7, but these problems are still present even on the new Microsoft platform. Furthermore, fetching is totally useless for solid state drive users, who may want to disable this function to extend the lifespan of the unit. For these and/or other reasons, advanced users might want to tweak the way Windows manages Prefetch and Superfetch, and TweakPrefetch is a very easy way to accomplish this.

TweakPrefetch is a utility coded in VB.net capable of managing fetching in Windows XP, Vista and 7. It allows the user to set separate parameters for Prefetch and Superfetch. The available options are:

• Disabled: completely disables fetching.
• Applications Only: fetching will only be applied to user started applications.
• Boot Only: fetching will only be applied to boot files (system files, services and startup programs).
• Applications & Boot: fetching will be applied to both applications and boot files (Windows default setting for Prefetch and Superfetch).