1299439 - The perf tool is really slow or unresponsive when used from the browser toolbox

Status: RESOLVED WONTFIX

(DevTools :: Performance Tools (Profiler/Timeline), defect, P2)

Description

[Patrick Brosset <:pbro>]

STR:
- Open a really simple page in a tab. In my case I only had one tab opened in my browser, on data:text/html,test
- Open the browser toolbox
- Switch to the Perf tool
- Start a recording
- Switch to the browser window and do something quick, like resizing the window a little bit
- Switch back and end the recording
- Wait!

I don't think it used to be this way, because I've used the perf tool in the browser toolbox a few times in the past, and I don't remember it being this unresponsive.

Now, it's basically unusable, it freezes for minutes (maybe forever, I haven't tried waiting mor than 5 minutes or so) and is unresponsive to user events.
It's obviously performing some really intensive tasks that prevents the whole process from doing anything else like:
- hovering over tabs in the browser toolbox doesn't even display them in dark grey like they normally do,
- trying to move the toolbox window doesn't work, or seconds later,
- trying to select an area of the timeline doesn't work.

In fact, after a few minutes, nothing works for me anymore at all and I have to kill the browser toolbox.

I tried using the perf tool in the *normal* toolbox too, and noticed that right after a recording was made, there's a bit of time when the tool is unresponsive. That's when it needs to load a lot of the data and draw the various graphs. But after a few seconds it works fine.
This initial processing that takes only a few seconds in a tab with a short recording is probably what takes minutes in the browser toolbox. Although I'm relatively certain that it didn't use to be this way.

Tested on the latest FF51 on a desktop PC with Windows 10. And a rather powerful one too:
- Dell Precision T1700
- Intel Core i7 3.6GHz
- 32GB RAM

Comment 1

[Julien Wajsberg [:julienw]]

Now that we replaced the old performance panel by the Firefox Profiler (see Bug 1668219) we're closing bugs related to this. If you see similar issues on the new profiler, please file another bug, and we'll be happy to have a look.

Filter on MASSCLOSEOLDPERFTOOLBUGS.