Currently Being ModeratedNov 14, 2012 2:10 AM (in response to lawrencehky)
If you only have the standard 4GB I recommend upgrading your RAM to 8 or even 16GB.
Make sure you uninstalled MacKeeper properly
The antivirus you have is probably not needed as Mac OS doesn't get viruses unless you basically download one on purpose. Not sure what the one you mentioned does but if it runs in the background I would definitely remove it as it is doing more harm than good.
If you make a new user account, log in to only that account, does it run slowly on that?