1. Please specify your computer’s configuration like CPU, Memory and Operating System. To find out that Right Click on My Computer and Click on Properties – You will be able to see all those information under the General Tab.
2. Are you using McAfee for the first time (if not) How long you are using McAfee on this computer?
3. Do you have any other security software (Antivirus or Antispyware programs) installed in the computer (E.g.: Symantec, AVG, Trend Micro, Spybot, Spyblaster etc…
4. If so you will have to uninstall them and check out the performance