Now, if you have an application that primarily runs unattended and performs the bulk of its operations in the background, you can improve its overall performance by configuring Windows XP to evenly distribute the processing power between the foreground and background tasks. To do so, select the Background Services option. Windows XP will distribute processing power among all running applications in long, fixed-length time slices.
Memory usage
The two options in the Memory usage panel allow you to control how Windows XP manages the use of available memory and system/disk caching. Here, the default setting of Programs makes more of the actual RAM in your system available to your applications by setting aside only 4 MB of RAM for disk caching.
For most situations, the default setting will be sufficient. However, if you discover that your applications are running sluggishly and you have at least 256 MB of RAM, you may want to experiment with the System Cache setting.
When you choose the System Cache setting, Windows XP allocates all but 4 MB of the available RAM to the system cache. The big performance gain here is brought on by the fact that this setting allows the operating system kernel to completely run in memory. Furthermore, having a larger system cache can, in many cases, improve the performance of an application by providing quicker access to multiple files.
It's important to note that while the System Cache setting initially grabs a majority of RAM for the cache, it's designed to dynamically manage the memory. So if another application needs some of the memory allocated to the system cache, Windows XP will make the needed memory available to the application.
A note on the System Cache setting
Enabling the System Cache setting actually enables the Large System Cache setting in the Windows XP registry. Thus, you don't need to manually change this setting by editing the registry, as you may have done in Windows NT or Windows 2000.
Virtual memory Of all the settings in the Performance Options dialog box, Windows XP gives you the most control over virtual memory. To help you understand the options that Windows XP makes available in the Virtual Memory dialog box, I'll go into the virtual memory concept in a bit more detail.
Some background on virtual memory Windows XP uses virtual memory to simulate more RAM than physically exists in your system. When you launch an application, Windows XP loads that application into RAM. If you load several applications at the same time, all the running applications must share the same RAM. However, as you can imagine, running all those applications together will require more RAM than is actually in your system.
In order to manage this situation, Windows XP monitors each application's use of the available RAM and locates sections of memory that are allocated to an application but aren't currently being used. Windows XP then moves, or swaps, these inactive sections from RAM and temporarily stores them on the hard drive in a file called the paging file.
