Feature request: better usePerformanceMark usage

[ryanwilsonperkin]

We've had several requests over the past year for a better understanding of usePerformanceMark:

• How do you use it to measure individual component performance? (you don't)
• Why doesn't the ID get used as the tag being sent to Observe? (we calculate the page tag based on URL instead)
• Why doesn't it actually seem to emit performance marks to be able to see them in the browser timeline?

We should try to address these issues as a group and solve the issues that folks are encountering when trying to use this tool. Ideally it should be possible to use this hook, or something like it, to be able to capture a common metric, with tags that you'd expect, and to use it not just on a page by page basis, but to also respect a stage like "component loaded" or otherwise.