I would like better in browser optimization tools

Lately I find myself optimizing a lot of sites that were slow to begin with or became slow during time because of excess design interactions, heavy code, or too much content. It would be great if there was a DevTool which would be more specific—and easy to read by newbies—that warns you (maybe even as you code) about potential savings. Audit is great, but lacks the ease of use I’m looking for