Chrome has a brilliant tracing visualizer. This allows you to provide trace file data to visualize what's going on in an app. You can read about it here.

Once you have a trace file, you start the visualizer off like this.

And load your trace file like this with the load option.

And you get something like this

It really is a fantastic tool, so I wondered if I could use it to help with logging in Apps Script. As a result, I've created a library that you can plug into Apps Script and profile your script to create input for the Chrome tracing tool. 

Here's how to use it