Sorry lol I'm at work. I misread and didn't even notice I made a type-o. Thanks mtngmr164 for the correction. Yes I meant decrease the time it takes to load. But no setting it to 3GB will make the load times longer. Anything over 3GB will reduce/decrease the load time. The default size of home before 1.3 was 3GB approximately. So 1.3 added this option to reduce the time it takes to load environment spaces.
From personal observation, the general startup time of home from the XMB hasn't changed(aside from 1.32's startup improvement time which no longer halts your ps3 during virtual item checking).