Theme slows site loading to a crawl

My website: https://www.betweenmars.com/start
Hosted by Dreamhost.
I’m using WordPress 2.7.1 with the Wonderland theme (with some minor adjustments – no sidebar)

I’ve tested my website on both a Mac and a PC, using IE, Firefox, and Safari. Regardless of the browser or computer, the website takes anywhere from 20-30 seconds to load. Scratch that… every page takes that long to load every time. The WordPress admin dashboard loads just fine.

I tried to figure out what could be slowing it down. I disabled all my plug-ins (I only have 7), but it still loaded slow. Eventually I tried a different theme, all plug-ins enabled, and it loaded just fine. 3-5 seconds. Great! But I like the theme I currently have and want to keep using it. I’m don’t know too much about website coding, but my assumption at this point is that there is something about the HTML or CSS that is making the site load so slowly.

Can anybody help me? What info do you need to look at to be able to help me figure this out?

Thanks in advance. ??

-LeTunaMan