From my reply to your previous post "you didn't say which CPU models you have, but based on the fact that you have two, those processors are most likely geared more for multithreaded apps and will have low end single threaded performance which is what minecraft needs, GHZ is not everything and this error means your CPU is lagging and can't handle it."
also if all cores are maxed out you have other apps running in the background slowing your CPU down, minecraft only uses 1 core, maybe a few more if you have plugins but only the plugins would be able to use several threads.[DOUBLEPOST=1404963224][/DOUBLEPOST]Try closing the apps in the background.