I have an old computer that was running very slow (almost unusable) and almost constantly at 100% cpu usage so I decided to fool aroung with the virtual memory.

The computer has 556mb RAM, I set the virtual memory to 1000/2000. After doing so, performance increased quite a bit and cpu usage went down to a reasonable level for the old box. Reading more on VM I saw that no more than 150% of RAM is recommended. To set it higher means that you are drawing from your HD and this means slow.

When I reset the VM to the recommended settings the performance was again slow so I put it back to to the 1000/2000 and it is once again doing relatively well.

My question: Is there a downside to setting the VM at this level and if 150% is the optimal setting why is the box performing better?

BTW, the computer in question was replaced by my current PC about 18 months ago. It was outdated but was performing fairly well at the time. It was about 6 years old and had been running 24/7 for the 6 years. After I replaced it I networked it to my new PC and I started turning it off for extended periods.

It seems obvious that lack of usage has had a detrimental effect on the overall performance of the PC. Why would that be so?

It seems that as long as a PC is kept clean and stored properly, less usage would extend it's life but that does not seem to be true.