Besides directly providing information that is relevant to a typical user, I'd hope such a solution would finally put some pressure on the companies to optimize their webpages.
And to repeat myself, I really do miss something akin to the icon that displays which tabs are playing sound -- not for myself, but because it would allow people to notice the difference between bloated and well crafted pages more easily.
I appreciate they prefer to automatically decide what is best, but I would prefer more gauges, at least as an accessible option. If you hide something behind an "advanced" label, it will just scare people off for no reason. It's not like configurations dialog aren't kinda barren and padded as is. Just fix that and then just put things there, neatly categorized and maybe even searchable, and explain them. People can drive cars and vote for politicians, but we can't trust them to read? Just about any image viewer or video player seems to think more highly of people than browsers of all things do.
And just let us allow tabs to grab all the resources they want on a opt-in basis. Why not?
* Before anyone brings up the inevitable economic argument - it wouldn't take a lot of man hours to do these things, I dare say it would just take one or two persons who are capable to be willing and allowed to do them. And compared to all sorts of things that browsers vendors made and get scrapped, you at least know tabs will always use ram, CPU and load assets over the network, so it's not ever going to be completely useless.