Posted 18 August 2012 - 06:02 PM
There is a minor lag and I don't believe this is the result of the image file size. Rather, I believe it's the result of our supersize function, which causes the background to be included in a jQuery script that must load before the background image.
I don't use supersize, and have a very wide background (min 2300px wide) and it loads before any scripts, so it's consistent with the site.
I'm not sure what to do with your situation as unlike my background, yours needs to be visible in the screen, no matter what the size. Mine are designed to allow for any portion on the sides to be clipped by browser width.
This may simply be something you need to live with (as I do with my totally receded hairline).