There are several ways to increase your system performance. Some of them give you big, most of them only little improvements. However, even the little improvements sum up to a considerable increase in system speed.

Speed Up Your CPU

Some CPUs in some Operating Systems can run faster than at normal settings. Here's what I've got for you:

AMD K6

enwa.exe
This little program will enable 'write allocate' in systems that don't already do that by their BIOS. It only works under DOS, Win3.1, Win95. Run it automaitcally from your autoexec.bat and it will change the specific registers of then K6 to the correct values. This program is completely harmless and doesn't interact with anything. msr.zip
If you need to change the MSR's of the K6 for 'write allocate' under Windows NT, you'll have to use this utility. Unfortunately it's kinda inconvenient. Please refer to the 'readme' and 'install.doc' for further instructions.

Intel Pentium Pro

ctppro.zip
Programs the PPro internal Memory Type Range Register (MTRR) to increase especially video performance, can enable the 'fast strings' of the PPro, which are disabled usually, due to a flaw of PPros with stepping 1, enables the write buffers of the Intel Orion and Natoma chipsets.
This program is of course another c't Magazine program and also of course from Andreas Stiller . If you've got a PPro you impossibly can do without it. fastvid.zip
Programms the PPro MTRRs for frame buffer and VGA memory area to 'write combined' and enables write buffers of the Orion chipset. os2.zip
Does the same as the above in form of drivers for OS/2.

Cyrix/IBM 6x86

6xopt074.zip
6x86 optimizer written by Mikael Johansson. Configures 6x86 cpu registers to increase performance. Additionally it enables Windows95 to 'see' the 6x86 CPU in the device manager. directnt.zip
Enables 6x86 cache under Windows NT 4. For all the Microsoft impaired NT users. M1OPT.EXE
This program configures the 6x86 for high performance M1.EXE
This program allows the user to view and edit 6x86 bit settings IBMM9.EXE
This program allows the user to view and edit 6x86 bit settings IBMM1.EXE
This program allows the user to view and edit 6x86 bit settings PUZZLE.EXE
For Optimizing 6x86-Based Systems, here the manual for it (PDF)