Comodo Firewall Only also includes an Anti-virus scanner?

Hi,

Even though I have selected to install commodo firewall only, it appears to show a Scan button on the userinterface which scans for virus. Im just wandering if this will have any performance impact as I only need a Firewall only as I have another anti-virus of choice which is installed and I use.

Also what is the difference between the above “virus scan” inside the comodo firewall only install, and a virus scan when I also install the comodo anti-virus package too?

Thanks in advance.