This bug was filed from the Socorro interface and is report bp-2655f1b4-a30b-445c-a375-ca1b80170820. ============================================================= Reported on Twitter: https://twitter.com/12thBattalion/status/899659052975882241 User reports that after upgrading to v55, the browser crashed "on the first video link i clicked".

Some additional comments from crash reports: Very slow and buggy, it was fine yesterday but it's suddenly become like this. Dailymotion and Youtube videos full screen especially copied link from Windows 10 News. https://a.msn.com/r/2/AAqdyeY?m=en-us Tried to close window and browser crashed I was attempting to open an email in yahoo-att mail when the browser crashed this has happened four times this morning. Currently not very high volume in 55.0.2, 63 crashes.

Probably due to the bitdefender extension installed?

(In reply to Kohei Yoshino [:kohei] from comment #2) > Probably due to the bitdefender extension installed? Quite possible.

Oops, wrong component.

I've tried to reproduce this issue on Windows 10 and the latest Nightly (57.0a1) Build ID 20170917220255, with Bitdefender antivirus and Bitdefender TrafficLight for Firefox add-on installed and I think I've managed to do so. I've opened 4 tabs containing youtube, cbs and dailymotion websites. In my case the used memory from all the processes sumed approximately 2GB and the system became very slow (in one case system crashed and blue screened). Here is a link to the Gecko profile of the issue https://goo.gl/1WYjxb . When I've tried to reproduce the same behaviour with the latest Firefox Release (55.0.3), I've got approximately the same results, including a full system hang (in that case I've opened 17 tabs). I've tried to do the same without Bitdefender antivirus and the Bitdeffender add-on and I haven't encountered any problems. Also, when I've tried only with the add-on installed everything works fine (no slowness or lag in animations). However, when I've tried to reproduce the behaviour only with the Bitdefender antivirus installed, the system became very slow. If I try the exact scenario described in comment 0, clicking on videos from cbs, dailymotion, youtube and fullscreening them did not result in a crash.

Alex, our QA people are seeing pretty significant slowdowns with Bitdefender enabled in comment 5. Have you seen similar reports from your users?