Kaspersky CANNOT eat that much of resources :P
Check for viruses or Spyware or any other background services eating many resources via the process list from the Task Manager.
Check for spyware/adware/malware by downloading spybot (www.spybot.com)
Disable any scans running from Kaspersky if there are.
And If your RAM is above 128 I dnt thnk Its a problem with Kaspersky..
If you turn off da protection, It'll be like you switched off the AntiVirus ..