If you think it's using too much of such, try uninstalling everything McAfee from the Control panel (you may need to remove each separate McAfee item shown in the Programs and Features section of the Control Panel), then use the McAfee removal tool from the link below to remove all remnants.

Note: Clicking on the link below will immediately start the download dialogue box:
http://download.mcafee.com/products/licensed/cust_support_patches/MCPR.exe

Once that's done, install something else, such as one of the free tools at the link below and use the Windows 7 firewall.

Avira (Currently among the best in detection rates, paid or free.)
http://www.free-av.com/en/download/1/download_avira_antivir_personal__free_antivirus.html

Avast
http://www.avast.com/eng/download-avast-home.html

AVG Antivirus
http://free.avg.com/ww.download-avg-anti-virus-free-edition

If you like the results without McAfee, you have your answer.

Hope this helps.

Grif