Firebug recently added an awesome new API; console.timeStamp lets you to create named “events” in the Net panel:

This technique requires manual instrumentation and isn’t as detailed as the Timeline panel in Chrome/Safari or a heavy-weight tool like dynaTrace, but it’s a nice, simple, uncluttered view compared to those other tools.

I used it today on a machine where I couldn’t install dynaTrace, I’ll surely be using it again. Unfortunately it isn’t supported in Firefox 3.6 and older.