Finally it all makes sense. Credit goes to www.lockergnome.com. - - - Processor scheduling The two options in the Processor scheduling panel allow you to control how Windows XP allocates processing power. As you saw in Figure B, the default setting in the Processor Scheduling panel is Programs, which basically configures Windows XP to focus the bulk of the processing power on the task, or program, that is running in the foreground. The Programs setting configures Windows XP to distribute processing power time slices among all running applications in short, variable-length bursts, and the program or task that is running in the foreground gets bigger time slices than those programs or tasks running in the background. 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.(Note: So this is basically the same thing that Vista does *by default*.) 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. When those sections of memory are needed by their applications, Windows XP retrieves them from the paging file and places them back in RAM. Of course, to do this, Windows XP will most likely need to move other memory sections of other applications from RAM to the paging file. As you can imagine, this swapping process is continuous when you use several applications at the same time, and it can be a big drag on overall system performance. Page pooled memory: it’s important to note that Windows XP uses a new virtual memory scheme in which it divides the physical RAM in your system in two sections—page pooled and nonpage pooled. In this scheme, the nonpage-pooled section contains crucial operating system and application files and is never sent to the paging file. Of course, anything in the page-pooled section can be swapped out to the paging file as needed. Altering virtual memory settings The Virtual Memory panel displays the size of the current paging file. To make changes to the paging file, click the Change button to display the Virtual Memory dialog box shown in Figure D. Figure D Of all the performance settings, Windows XP gives you most control over virtual memory. In the Total Paging File Size For All Drives panel of the Virtual Memory dialog box, the Recommended size for the paging file is based on a formula that multiplies the total amount of physical RAM in your system by 1.5. As you can see on this example system, which has 512 MB of RAM, the Recommended size for the paging file is 766 MB. Paging file size: simple math will tell you that this value should be 766 MB, which is indeed the amount being allocated, but due to the way that Windows allocates memory, only 511 MB is actually available to the system. Thus, 766 MB is listed as the recommended size. You’ll also notice that Windows XP specifies a minimum value of 2 MB—Microsoft strongly recommends that you not set the initial size lower than that value. To improve system performance by adjusting virtual memory settings, you can increase the size of the paging file, or you can move, or spread out, the paging to other physical hard disks. Increasing the size of the paging file is easy: Simply enter a larger number in the Initial Size text box. Then, double that figure and enter it into the Maximum Size text box. To enable the new paging file, just click the Set button. The best performance increase will come from moving the paging file from the C drive to another hard disk. Of course, this requires more than one hard disk in the system. Keep in mind that you won’t boost performance by placing the paging file on another drive partition on the same hard disk. The performance boost from moving the paging file to another hard disk comes from the fact that while one hard disk is handling operating system functions, the other hard disk can simultaneously handle paging file requests. To move the paging file, select the C drive in the Drive list. Then, select the No Paging File option and click Set. Next, select the other hard disk in the Drive list. Then, select the Custom Size option, type the appropriate values in the Initial and Maximum size text boxes, and click Set. When you click OK, you’ll be prompted to restart your system. Use an old hard disk for your paging file Finally, if you’re like most IT folks, you probably have a bunch of old hard disks sitting in a box in the back room. These old hard disks aren’t viable for today’s operating system and software disk requirements, but they’re perfect for a paging file. Just add the hard disk to your system as a slave, format it, and configure Windows XP to use it for the paging file. [Greg Shultz] - - - One thing that I never understood before, but I do now, is that the reason you should always have a pagefile is because that gives Windows someplace to toss the unused extra memory pages that most programs request, even though they never use them for anything. This way, Windows can use the real RAM that would otherwise be tied up with tons of never-used memory pages for something useful instead.