Page loads very slow due to long WAIT time. How can I reduce?

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http://serverfault.com – First things first, I don't know much at all about server configuration. But we have managed support, so if I can get some ideas to point them in the right direction, hopefully I can get this issue figured out. I have a website that has loading extremely slow, due to a long WAIT time. What's really odd about this is it isn't happening to other websites on our server, and even more so, when I copied the site to another domain on our server (as a sub-domain) the wait time was reduced back to normal. You can compare the two sites (which are 99% identical) via this link: http://tinyurl.com/9dn (HowTos)