XP, resources used
use network offline
By having the network do things itself that the local computer usually does, the CPU processes needed to maintain a network connection are lowered. This does not work on all cards, and it can cause network connectivity problems on systems where the service is enabled but unsupported, so please check with your NIC manufacturer prior to enabling this tweak.
thumbnail cache
Windows XP stores a "thumbnail" of graphic images or the first frame of the video and makes it into an oversized icon for the file. Those files can either be created each time you access the folder, or they can be cached. The thumbnail caches on systems with a large number of image and video files can slow the process down significantly.
16 bit processes
The 32 bit version of Windows XP will usually only open one 16-bit process and put all 16-bit apps running on the system into that process. This is necessary for some older applications that run together and share resources.
But most 16-bit applications work better when they have their own dedicated resources. With the following registry change, the process is put in a "Win16 VDM" (16 bit Virtual DOS Machine) which doesn't allow any interaction with other processes. This is also called a WOW (Windows On Windows) process.
