I am using the blog MU theme, and I was wondering why

I am using the blog MU theme, and I was wondering why the load time on my site seems to take so long. I know it may have to do w/ the image size i've choose to use on the homepage, but are there any other reasons for slow load time w/ this theme?

Should I turn off certain plugins or anything else? Just curious what are the may things I need to focus on to achieve faster load times w/ my wordpress site and specifically the Blog MU site.