It’s really nice nowadays. You can record it, and then easily select parts of the timeline, zoom in, see the function call breakdown, etc. Many of the features were available before, however it’s now all in one spot. With the experimental timeline settings enabled, you can also see arrows where an event started, and on which frame it ended - and which function it called. Etc.
There is an extra live performance monitor tab - that is always running. But it might be harder to find. You need to open the Console, click on the Console’s 3 dots > More tools > Performance monitor
For experimental features open the Console, click on the Console’s 3 dots > Settings > Experiments
Then press SHIFT 7 times.