In order to test multitasking performance, we ran the World in Conflict: Soviet Assault benchmark while an AVG anti-virus scan was running in the background.
Here is another area where we can see the 6MB of shared L3 cache in the Phenom II models come into play. The Phenom II X2 550 and X3 720 demonstrate a large advantage over their Athlon II X2 and X3 counterparts. However, the Athlon II X4 620 beats out all of the competition when these programs run concurrently, despite a complete lack of the shared cache memory. Even when overclocked to 3.77 GHz, the Athlon II X3 435 barely beats the minimum frame rate of the Athlon II X4 620. The higher number of CPU cores wins the day when multitasking; no surprise here.