Site Speed

My Wordpress/Buddypress site currently takes around 5/6 seconds to load. I have spoken to my host iPage and they are going to install the W3 Total Cache which they think will speed it up. I am considering moving to another host if necessary as the page load is just too slow though I don't really know that the problem is.

What do you think could cause the site to load so slowly and do you think another host might be better?