cmdagent uses 100% CPU during scan | AntiVirus Help

Just installed AV on a Pentium Dual Core with Win 7 Ult 32.
The scan function uses 100% CPU and the temperature goes up to 70°C,
at which point CoreTemp begins its emergency shutdown procedure.

Is there any way to throttle the scan to use only 50%, (and NOT 100% of one core and 0% of the other)?
If so, I couldn't find it.

So I googled for something that might do it more generally, and found Threadmaster (which runs from the command line) and then ThreadmasterGUI which has a nice simple window. I limited cmdagent to 50% and set the scan going, but that 50% is measured for every 30 second interval, so at first it still uses 100%. Changed the interval to the lowest - 10 seconds, but it doesn't seem to help. Perhaps there is some complex interaction between Win7's hyperthreading/scheduling and ThreadMaster, but it doesn't given me continuous 50% usage on both Cores.

I was amazed on coming to the forum that this isn't covered.