Startup profiling

[bikb]

Hello,

first I want to say thank you to all developers and contributors of Mozilla software and this project of course.

I want to profile a firefox version 115 ESR.
It was build from sources and recompiled by VMWare Thinapp to put it in a sandbox.
After recompiling with Thinapp something changed with startup procedure.
I start Firefox with profile manager.
I have to wait a long time to the profile dialog arises and after selecting the profile.
This behaviour is new to versions greater ~ 100 of firefox.
Firefox 94 did not have this problem for example.

I have enabled the capture button as described in the docs.
A first test if the profiler is working was fine.
I have added the environment variable MOZ_PROFILER_STARTUP with value 1.
I had expected that the profiling was startet and the button is enabled after startup.
But as the docs describe this isn't the case but the profiler starts as early as possible.
After Firefox Window is available I have to start capturing by clicking the button.
After stopping it doesn't show anything earlier the time I was hitting the button.
It shows 2 seconds.
But the startup lasts more then a minute.
So what is going wrong? Why is the profiler not capturing the startup?
Could the sandbox be the reason?

Thank you.

┆Issue is synchronized with this Jira Task