How about a standard how heavy the site (and other meta details) before it is loaded within the html spec? In this way, a user can opt out to continuing to bro

How about a standard how heavy the site (and other meta details) before it is loaded within the html spec? In this way, a user can opt out to continuing to browsing with details from say a short response header. Is something like already proposed anywhere, or not really a solution to the problem — thoughts?