Here's the profile that hallvors originally gathered: https://cleopatra.io/#report=ec6ca9e148231495653c86f20d1a1cb4f7037822&selection=0,1,29,3,93,94,95,96,97,98,99 Hey hallvors, is it possible to get another profile but using the Gecko Profiler add-on instead of the DevTools profiler? A lot of the DevTools instrumentation is showing up in the profile and is adding a bit of noise. I imagine that's often filtered out when profiling an individual page, but when viewing it in Cleopatra, it distracts. One thing I _have_ noticed looking at this profile is that there are some sync IPC messages being sent from content to the parent to query the dimensions of the screen that it's on. These sync messages, if they occur during an animation, would certainly cause a stutter (I'm seeing an instance of 172ms of waiting for that sync IPC message to complete, for example). Making those screen dimension IPC queries non-synchronous is being tracked in bug 1194751.

Profile #1: this is just re-loading the main UI (this doesn't really feel slow though) https://cleopatra.io/#report=55a2f91b47f227672d9043e8ee49b7af847521ed Profile #2: creating a new E-mail, discarding it again (this feels a little laggy): https://cleopatra.io/#report=7e278404b584d889016ec8cad954c0ccdc6e5abb Profile #3 - I've forgotten: https://cleopatra.io/#report=a181b204a6d445f70e1d380130ba3b4ff6dea4cf Profile #4 - click "trash", select all (10) visible items with the checkbox in the header, click "Move" and select inbox: https://cleopatra.io/#report=db2d64f48461735caba085d3ebb4c9089d260a3d

Using the Outlook.com UI with my (lightly used) old Hotmail account does not feel that slow to me. In the webcompat issue it was mentioned that the site may be disabling certain transitions and animations to speed itself up in Firefox.

Per OWA pilot test report [1], no big issue has been found in OWA. [1] https://drive.google.com/open?id=1EFLyUUFHdktOVyEz8zQACY_lRfz69_hwBiCeetQe9iE Close bug for now. Please reopen when you find critical issue.

(In reply to Bobby Chien [:bchien] from comment #4) > Per OWA pilot test report [1], no big issue has been found in OWA. > > [1] > https://drive.google.com/open?id=1EFLyUUFHdktOVyEz8zQACY_lRfz69_hwBiCeetQe9iE > > Close bug for now. Please reopen when you find critical issue. Note: This test and results is for Office 365's Outlook and not Exchange Outlook Web App (OWA) which most problems are reported against. We should either change the title of the bug to remove the 'Exchange' piece or we should open something new for testing against Exchange versions of OWA. The challenge with the latter is the setup of different Exchange setups and versions.

Thanks. Hallvord and Dees. I will reopen this, and keep original thread.