Since the cpu has very little to do with memory, you need to see what programs require constant access to the cpu. If the cpu isn't fast enough, get another. If the cpu cannot handle the thread process, get one that can.
HI my computer is running at 100% i thought it was a virus so did a reinstall of windows.i deleted all the old partitions and created a new one? it lags when the installation is in process so i turned it off and when i started it back on and it continued the installation. after the installation was complete i checked task manager and it was still at 100%? and ideas??