usually a slow computer can be from you doing too many task or doing task that take too much processing power. also since your os is on a usb and not in a harddrive, the way the computer reads the info will be different. a usb is like a basic reader whereas a dedicted harddrive is made to be read muc faster. like if you could compare rpm (even tho usb doesnt have spinning parts) the harddrive is more efficient for it as well as launching programs