Try it. You can't break it if you have a copy of the original to go back to if it doesn't work. Though to me it looks like a function to scale videos and images, not the page itself. Then again, if it's loading ginormous images and resizing them after the browser is loading them, I suppose that could cause some jumping since as they get resized smaller, the page length gets smaller. You can safely comment that whole function out and see what it does.
The rest of that script seems to deal with the annoying text-changing thingie at the top.
The other major script is the one that makes columns. Since these are all separate scripts, you could probably easily comment out one, then the other, do see at least which script is making webkit jump.
After that, finding the function is probably easier. You may want to keep the column js but remove the image resizing js (and instead make sure your static copy of the image on your server is already the correct size before the browser even asks for it).
Also, you liked the way the theme looked. Mostly, it's a minimalist design. You could have plain content and style it that way instead.
Oh jeez after several reloadings of the page I suddenly see these posts I kept hearing about. Bleh. The idea of requiring scripting just to read plain-text content is silly. Wonder who came up with this theme.
I've also noticed that my footer info (RSS link and ©2011 link) at the bottom bump to the far left and bottom with no margins on individual post pages, but seem fine on the homepage, any thoughts?
On the pages where the footer is more in the middle, the "extra" div (which contains the footer) is inside the box called #container. On the pages where the footer is much too far to the left, the "extra" div is outside the container. Since the container is centered, the footer's left-margin of 200px is 200px from the left side of the centered container, but when it's outside the centered container it's 200px left from the body/viewport/page. That one would indeed be a PHP issue, since your PHP templates are placing your boxes in the order they end up in on the page.