I found YSlow helped me effectively optimize the loads speed there is so much that you can do to help you with this. Hows the optimization going? My tools of choice were firebug and yslow - I also installed pagespeed from Google Webmaster Tools when doing this work.

Hi Brett - when I have been optimizing the loading of one of my wordpress sites I have found YSlow is effective. Have you used it?

Robert gives you a very good answer; a page with low ranking is ideal for being improved through optimizing the on-page factors and gaining links to your pages. If you have a blog linking to these pages is a very good idea to bring them to visitors attention again.

Just to reinforce this point - Thankfully page ranking doesn't carry over otherwise there would be a lot of us in this industry struggling!

In relation to internal linking I would look at where these pages sit in your site architecture in terms of links to them - are they prominently linked to in your navigation or are they buried deep in your site. If they are buried deep would you be able to include them closer to the top of the site navigation (in terms of including them higher up the navigation levels, such as only taking one click to get to your low ranking pages from the homepage) with approrpriate keyword anchor text linking to them? Depending on your site this is not always appropriate but it is a concept worth considering as it will make a difference in my experience.