The page loads slowly because of all the unnecessary table tags. No browser can render that in one pass, regardless of DOCTYPE. Your entire layout could be better accomplished, and load quite fast, by using CSS for the layout.
As it is, your site is only using CSS to style a table-based layout. While it is possible to use the 'table-layout:fixed' rule and <col>/<colgroup> tags to make it load in one 'browser pass' it's quite frankly less work to ditch the tables altogether.
For now, though, if you want to fix the 'jump' you'll need to change the first <tr> tag in your second table (the one under the header) to:
Do this on all your pages, even the ones which don't exhibit that behavior, for maximum cross-browser compatibility.
Ha! I beat the_pm to the punch for once! Where is Paul, anyway?
Eric J. Bowman, principal
Bison Systems Corporation coming soon: a new sig!
I'm just a poor, unfrozen caveman Webmaster. Your new 'standards' frighten, and confuse me...