1134055 - Jank when switching to tab with data: URL image

Status: NEW

(Firefox :: General, defect)

Description

[Vladan Djeric (:vladan)]

STR:

1. Convert a >1MB image to a "data:" url, e.g put http://upload.wikimedia.org/wikipedia/commons/4/44/Abraham_Lincoln_head_on_shoulders_photo_portrait.jpg into http://dataurl.net/#dataurlmaker
2. Paste the resulting data: URL into a new tab
3. Switch between the image tab and other tabs

Expected: Tab switching should be smooth, as if the tab contained the regular .jpg URL of the image

Actual: Long jank when switching to the data: URL image. Reproduces 100% both on e10s and single-process Firefox.

Profile of Jank: http://people.mozilla.org/~bgirard/cleopatra/#report=d3962e40953bdd3a720ad924edfb93b68dddddbc

* note sampling resolution is 50ms

It looks like most time is spent in building a text run for the long URL (presumably to display it in the location bar), followed by time spent calling into the Content Prefs service and drawing the text.