Change order of Javascript content loading on my Web page

See my Wordpress blog at histalk2.com. The left column contains only widget-driven ads from my adserver. I would like the information in that column to be loaded only after the main content in the middle column has loaded. My page loads slowly and I would like readers to be able to read the content as soon as possible after hitting the page, with the ads loading afterward. I've heard of a "defer" option in Javascript that may accomplish this and I'm sure there are other ways as well. I need the solution to work in IE, Firefox, and Chrome. I'm interested in any other easy speed-up options you can suggest. I've tried Wordpress caching plug-ins an would prefer to not use those again. I'm also not interested in making major design changes or revising how the ads work.