To all those suffering from performance issues with safari, flash and overall sluggishness of the system try to turn off Airport and turn it on again. After you turn Airport off the CPU (actually the core that goes through the roof) goes back to normal, and the system is smooth and buttery overall again. In my case CPU usage went from 68 to 1.25!! right after Airport was turned off. Please give it a try and report here if that works for you guys.