One useful way to take advantage of this might be to just serve your site at a lower resolution if the HTTP header is defined to reduce bandwidth use. If you're using 500px wide banner images on a 1000px grid, size that down for the Safari preview but scale everything so that it's still representative of your site.
One would think that the time it would take to implement that would be far more than could ever be conceivably saved by bandwidth reductions, except for perhaps the very largest sites.
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One useful way to take advantage of this might be to just serve your site at a lower resolution if the HTTP header is defined to reduce bandwidth use. If you're using 500px wide banner images on a 1000px grid, size that down for the Safari preview but scale everything so that it's still representative of your site.
One would think that the time it would take to implement that would be far more than could ever be conceivably saved by bandwidth reductions, except for perhaps the very largest sites.