tracking payload size of third party content

Is there a way to track the size of payload that 3rd parties such as adservers are adding to your site, or rather the end users perception of your site as it is delivered straight to the browser (in most cases), via some nifty javascript?
Utilising a tool such as to monitor/test a site requires an element of luck to catch an offending ad or intermittent large file.

You can track timings for elements or pages (particularly easy if the ad is in an iFrame) but I’m not aware of any way to track the size of things delivered on the wire from javascript.

I feared as much. I think there is a filesize attribute in ie that you can call from javascript…but that seems to be more for local files rather that finding the size in bytes of the document and its elements that has just come down the wire.

thanks anyway

You might be able to interface with Firebug and get info from anyone that has it installed (or more likely, has it active) but that would only get a TINY part of your customer base :frowning: