Why my computer slow?

Q. Why my computer slow?
A.
1. Open Task Manager; how? right click on the taskbar-> select Task Manager
2. Click on tab Performance and check CPU Usage and Memory Usage; The Memory usage
shouldn't be more than Total Physical Memory, if more - computer will work with the
virtual memory using Hard Drive space and everything will be slow; CPU Usage shouldn't be
more than 50 - 60% for good computer speed (average 10%), if more:
3. Click on tab Processes, check 'Show processes from all users' and see from CPU column
what program takes maximum CPU time (if System Idle Process is 99% and all other
programs take 1%, this is best for high speed). Try to search that program using Google to
understand what that program is.
Sometimes you download some plug-ins or other programs which running on Startup
Windows and take time (worst case is spyware: remove immediately).
If some programs you don't use after Startup you can remove it from the Registry Editor.
(The program will exist and run manualy but not on Startup).
How?
4. Go to Run -> type msconfig-> OK -> Startup tab.
You will see all programs running on Start up Windows. Uncheck if you don't use it.
The other step is to check what services started on startup.
1. Right click on My computer -> Manage -> expand Services and Applications -> Services -> Status -> Started.
2. Check each Service Started. If you don't need it: double-click on unusefull Name and change Startup type to Manual or Disable.