Promising but very user-unfriendly Rated 3 out of 5 stars

Ok, I've just tried this add-on and sadly I couldn't get it to work. I get a "Profiler: Running" text on the lower right of the screen and a popup menu if I click on that. The popup menu has several buttons, but so far none of them did anything useful.
Unfortunately, there is absolutely no support for this add-on, not a even a full description of its features.
However, it does seem to work on the developer's computer and from the screenshot this add-on looks very promising. I've been looking for a profiler add-on for Firefox ever since XUL Profiler became obsolete, and this is the first one I found that seems to have those features. So I really wanted to like it. Maybe it's my fault that it's not working on my PC, but without some sort of help manual I don't think I'll be able to decipher how it works.
Anyway, I'm giving it 3 stars because it looks promising and (I think) it's the only add-on that can currently profile Firefox

This review is for a previous version of the add-on (1.9.7). 

RE: Promising but very user-unfriendly

I've got an update coming as 1.9.8 that will fix this unfortunate regression. It's awaiting review. Meanwhile you could try the latest build off my github.

I'll be writing more documentation for this add-on soon. Right now you can take a look at:
https://developer.mozilla.org/en-US/docs/Performance/Profiling_with_the_Built-in_Profiler