Created attachment 8869392 [details] profile.json User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:55.0) Gecko/20100101 Firefox/55.0 Build ID: 20170516103005 Steps to reproduce: There is an issue involving expanding progress rows on myanimelist which results in the UI and content hanging till it finishes doing whatever its doing. This will require an account with myanimelist, and a series added. I have created one for this purpose https://myanimelist.net/animelist/Nightly55Bug Username: Nightly55Bug Password: *"2Kb!2sQ^'S*5ry Actual results: Clicking on the X/X will expand a text box in which you can add the chapter/episode yourself. On recent nightlies, clicking this will result in the entire browser being unresponsive. The test account does not reproduce the issue, but may provide a means to understand why it is occurring on more heavily used accounts. It seems to involve the fact that the text entry box causes the rows beneath to be shifted down. Expected results: The ep/chapter entry box should appear near instantly instead of taking a long time processing it. Notes: Reproduced in a clean profile Not reproducible in Firefox 53. Not reproducible in Beta. I have also attached a performance profile, not sure if that helps.
I can reproduce it with FF55 but it's very sporadic.