Is the problem when you use all those add-ons, or any of them? Have you contacted their support? Some add-ons do not work with some other add-ons.

The problem occurs when I install one add-on only. Then if I had another the startup is a bit longer. I haven't contacted their support because it is a problem of FF : each add-on has an impact on the startup time. If I enable the three add-ons I mentionned above, they work well.

Could it be a problem with e10s? I may open a bug report (?).

Any one, or a specific one? I've called for more help.

Any one... As I said each of these add-ons slows down the startup.

You may find more information and help on using Extensions in development channel builds like Nightly and Aurora at http://forums.mozillazine.org/viewforum.php?f=23 as this is one of the places where Firefox Testers tends to hang out vs here. Note if you do not have an account there, new members first post requires post moderation (due to spam attempts) and then can post normally.