Streamlining a fat and insecure portal based community website

We have been running our community portal using DUPortal Pro from [login to view URL] for a few years now. But we suspect the code is a little fat and may have a few security holes in it and we would like to get someone to spend some time going through the code and recommending ways to improve it. The site has a large number of pages but we're hoping someone can streamline about 25% of the pages and then we'll do the rest. You can download a FREE copy of the DUPortal at [login to view URL] and take a sneak peek at the code and then let us know if you're interested. We've done a lot of little modifications to the code to make it do exactly what we want, so we don't want any new features just maybe making the site less resource intensive and more secure. At the moment our website host has disabled our site as they claim it is using all of the server's resources and thus causing problems with other customers on the same server. So this is quite an urgent job.