Does your Firefox take a long time to shutdown? Do you get “Firefox is already running” messages when restarting? Well the Firefox Performance team would like to fix that, so please keep reading!
The Gecko Profiler extension now has a new feature called the (Automatic) ‘Performance Reporter’. If you opt into this feature, the profiler will watch your browser for any performance hiccups and will automatically send a detailed bug report for the Performance team to fix! Currently, this Performance Reporter feature monitors only your browser’s shutdown behavior and only sends us a report if shutdown takes longer then 1.5 seconds, but we would like to extend it to cover all aspects of Firefox performance. The reporter works in the background and does not interfere with your use of the browser.
The performance reports contain the URLs of the tabs you have open and are uploaded publicly for processing, so if you are not comfortable with communicating this information, do not enable this feature — we understand! We have taken precautions to never record anything coming from a private browsing window. Also, please note that the Performance Reporter is not related to Firefox’s Telemetry or Health Report features which never send any sensitive information such as URLs. The Performance Reporter is different — it collects very rich data so we can get a complete picture of any performance problem.
How do you turn this on? Make sure you’re running the latest version of the Gecko Profiler which should read as v1.11.17 or later. If I have not scared you away great, turning on the Performance Reporter is as simple as flipping ‘profiler.performanceReporter’ in about:config.
Benoit Girard's Blog 
Flipping a vaguely named about:config pref should not cause Firefox to send sensitive information to Mozilla 😦
Yes thats a valid concern. I was thinking about that but I dismissed it thinking it that users shouldn’t go around flipping random prefs anyways. I might make it more explicit to make sure the change is intentional.
I can understand the concern, but a user has to install an extension for profiling Firefox from GitHub and then set an obscure pref in about:config to enable this behavior. It’s not going to happen by accident, you essentially have to read this blog post
Does this require profiling to be running (as in, recording samples to the buffer) for it to work?
If that’s the case then I’d be hard-pressed to do something like that since the profiler regresses performance by 20-30% on Windows (according to benchmarks), makes Firefox use the CPU 1-5% while idle and also makes the browser subjectively feel more sluggish.
This is also the reason that precludes me from running the profiler all the time, allowing me to catch information on unreproducible transient hangs.
Yes the performance impact is much worse on Windows. We’ve landed a change about 2-3 weeks ago to lower the overhead but it’s still higher then mac.
You if set profiler.enabled:false it wont turn on by default but it will start itself when you’re shutting down to collect a profile and send it when you restart.
That’s neat then, thanks.
When restarting (for example for an update) the profiler is enabled on restart even when profiler.enabled was set to false.
On second thought, that might just be the case when MOZ_POISON=NO
I honestly dont care about what i sent to Mozila. Because out of, Apple ( Which I like, ) Microsoft, Google, Facebook, I trust Mozilla the most.
It would be nice if the Profiler could collect as much data as possible to speed up the development.
Can I see my own reports somewhere?
Try with Ctrl+Shift+O or clicking the “Analyze” button you get in the extension’s panel (near the search bar)
Does this work on FreeBSD or is it not platform agnostic?
The profiler has a whole isn’t ported to BSD. The profiler is changing thus we would need someone to maintain it on BSD. Until then this feature wont work there.
My xpi read 1.11.10 which is proberly older then 1.11.17..
where could i find the latest version.
I think the 1.11.17 was a typo and intended to be 1.11.7