#WebComponents I mean, I found HTML pages that contained words about the devtools. They were not elucidating. I was unable to map anything I was seeing to my code in any meaningful way. No mark/measure i.e. disconnected from performance API, and just got the vibe that no one used them.
Usually when tools are widely used, there are resources online to help people understand them. Not so much for the dev tools perf stuff. Lesson: build simply in a way you can understand easily what's happening.