You won't get a performance benefit just by disabling cores. You have 6 cores, each of those run at 3.98GHz, if you disable a core, the remaining cores will continue to run at 3.98GHz. The only time I can see people disabling cores would be if they are overclocking as disabling cores *may* give them more power or thermal headroom to overclock although it's not commonly done in regular use. You'd be best just to leave all cores enabled.