How to run a performance analysis on a WebExtension?

I’m developing an addon and it’s becoming very sluggish with the latest update I added to it and I want to see which part of my code is slowing it down.

I went to open the performance tab in the developer tools but it turns out that it is disabled when debugging addons.
There is even a stackoverflow and a bug report about it:

I tried the “solution” suggested, regarding going to profiler.firefox.com but I can’t find my addon in the profiler results and it is also ridiculously buggy and constantly crashes. It’s just ridiculous beyond words.

I was wondering how everybody else does this.