Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:128.0) Gecko/20100101 Firefox/128.0 ID:20240521094553

Today I've noticed that opening the DevTools panel can take a very long time when a good number of tabs are loading in the background (including pinned tabs).

Here a profile recording of such a situation: https://share.firefox.dev/3QWmTog (due to privacy all resource names are removed)

Steps to reproduce:

1. Open 2-3 dozen or so of tabs and load content which takes a bit to reload like Google docs, spreadsheets, presentations and others
2. Pin around 10 of them
3. Open a new tab and load https://epaper.tagesspiegel.de/
4. Open the settings and go to the Enhanced Tracking Protection settings, enable custom settings and change the setting for Tracking Content
5. You will be asked to reload all tabs, click on that button
6. Switch back immediately to the tab from step 3
7. Try to open the DevTools panel

With step 7 I see an empty panel as nearly as long as all the other tabs are reloading even through the current tab has already been loaded. When the last pinned tab in my case a longer Google document has nearly finished loading the DevTools panel fills step by step with content.

Another profile for a similar slowness: https://share.firefox.dev/44qV90P

Try to reproduce the STRs

My profile seems stuck on a tab doing GC for a long time, maybe unrelated to devtools. So this bug might be different.