You won't believe this, this is a crazy bug :-)
We have our own Phabricator instance. When I open certain Maniphest tickets, I see my CPU goes berserk - it eats 40% of my CPU constantly. Once I switch to a different tab, the CPU goes to almost zero utilization. For other tickets, though, the CPU is idle as well. Only some of them cause problems.
A colleague of mine sees a similar behavior (with 90% CPU utilization constantly), but for different tickets. I was very confused by this, and I've found the source of the problem after some debugging.
The CPU goes crazy if:
- the top bar (with your avatar icon) is displayed and
- there are other your avatar icons displayed on the page at the same time - e.g. you created the ticket, or (possibly, not tested) there are some comments from you on that page
If you scroll down the page a bit (so that the top bar is no longer visible), the CPU goes idle.
If you shrink the browser window so that no other your avatar images are visible (comments etc), the CPU goes idle.
If you use Firefox web development mode and remove either the top bar avatar image, or all other your avatar images on the page, the CPU goes idle.
If you log out (i.e. no avatar image displayed in the top bar) and see the same ticket again, the CPU goes idle.
Here's an example page that hogs the CPU for me (but not for my colleage):
Here's an example page that hogs the CPU for my colleage (but not for me):
I have verified this problem on several different machines running Fedora 20 and Firefox 29 (a clean profile tested as well), also several Phabricator user accounts. It does not happen with Epiphany (webkit-based). The version of our Phabricator is 20140518.git3a81f8c. I haven't seen the same problem with Differential tickets, just Maniphest ones.