There are a number of BIOS settings in your system which affect
the overall performance of the machine. When these are tweaked correctly, performance can
increase quite a bit. Lets look at these.

• Set Optimal Bus speed Settings. This is first because its
  most important. The bus speed of the system directly affects how fast it is because it
  affects the communication lines between the parts. The processor speed relies on the bus
  speed. Processor speed is the result of the bus speed times the multiplier. A multiplier
  is the number of times faster the processor is than the bus. You want to use the fastest
  bus speed supported by your motherboard. In order to do this, you may need to lower the
  multiplier to relate to the CPU speed. This is controlled by jumper settings on the
  motherboard, or in SoftMenu if your board is jumperless.
• Enable the internal cache. Processors have their own
  internal cache which operates at the processor’s speed. The newer chips have larger
  caches. Always have this cache enabled. This is controlled in the BIOS. It helps
  performance quite a bit. If you can’t enable it without problems, it is a sign of a
  definite hardware problem.
• Enable External Cache. This cache sits on the motherboard
  and lies between the RAM and the processor. Some comes on a small card that fits into a
  short little slot, but most newer motherboards have the cache built on. Some have 256K,
  others 512K or higher. Make sure this is enabled.
• Enable Fast A20 Gating. This is a confusing subject I
  don’t feel like talking about, but enable it for a small performance boost.
• Enable Global Chipset Features. Enable this BIOS setting
  for faster performance. Not all chipsets even have it, so its no big deal.
• Make sure all the RAM that can be cached is being cached.
  Most chipsets have the capability to cache up to 64MB of RAM. Some chipsets, like the
  430HX, can cache more. In any case, enable this option to cache whatever it can. If this
  is a problem, there may be a memory or motherboard problem.
• Tweak the Memory Timing. Most BIOS provide an option to
  set the timing, or speed, of the memory in the system. Setting this as fast as possible
  can aid performance. Most BIOS do it automatically. Its best to avoid setting it too fast.
  Most typical RAM has a speed or 60 ns. Whatever yours is, set it to that.
• Finally, if you have flash BIOS, get the latest BIOS
  version.