Optimize AdSense Load time
WebmasterWorld forums have a thread about possible lags on pages displaying AdSense. I have noticed this but not on all designs, sometimes it take time until the adsense is displayed then the rest of the page, menu or other. To avoid this here is some suggestions
If you position your layers through the stylesheet then you can load them into the browser in the order of content and load the ads layer last.
Pack your ad units into a div, and give that div a fixed size in pixels (the same size as the ad unit, of course). This allows the browser to position that div and to immediately continue with the rest of the layout.
