Solutions for Banner Ads

Flash has served as the de facto standard for banner ads for more than a decade.
Years ago, when bandwidth was a tiny fraction of what it is today, the ad industry codified a set of standards for banner ad file sizes. A common limit was 40kb (sometimes even 30kb) including all images, fonts, animations and scripts which Flash compressed into a single amazingly small swf file. 
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In HTML5, however, a library can be dropped onto a CDN (content delivery network) and shared among all banners.
File size limitations should be applied to the banner-specific assets.
Ad networks and publishers can put a certain subset of tested-and-approved libraries onto their CDNs and exempt them from file size calculations.
http://greensock.com/html5-banners