Do a ctrl-alt-delete Keys thing on the keyboard(all three keys at the same time). This brings up your Windows Task Manager. Now look in the processes tab. I personally have 35 programs running with only Firefox open at this time. I also am varying between 0 and 5 % on the CPU there. This computer is my internet computer and is a Athlon 2400. It is quite fast on the internet. It is trimmed down of all bloatware as much as i possibly can do. Perhaps you have a program(or programs) that does a lot of activity( like messenger)that will raise up the CPU usage. I have noticed that XP seems to get slower everytime you update the critical updates. Also the more programs you load on the computer the more you have that will slow it down.
I have the luxury on not having to update most of my computers. They never get on-line so i really dont need any updates, they dont need defender installed, or antiviruses, or any other programs that slow your computer down just to protect it. I also limit my computers to 20 installed programs on each.
You should expect your computer to slow down over time and with added programs. Running defrag more often does help. Uninstalling programs you do not use also helps. You need to think of computers the same as automobiles. The lean and trim sports cars are the fast ones, and the Rolls Royces are large, heavy and slow. They both get the job done but in different ways. You just need to take your pick of which you want.
If you want to look into what may be causing your computer to slow down, i would download Microsoft Process Explorer and learn what does what in your programs.http://www.microsoft...ssExplorer.mspx