Task

1. Start with open IMAP inbox (~1,000 messages), threaded.
2. Begin profile.
3. Sort folder by sender.
4. End profile.

Should collect:

- content model teardown cost
- sorting cost
- content model setup cost

Profile shows:

All CPU time spent on main thread (248msec).

  - 44% of the time (110msec) spent in one call to
    XULSortService::Sort(). Of that:

     - 60% of the time (65msec) is spent in 4,772 calls to
       XULSortService::InplaceSort(). This calls GetNodeValue 11,508
       times, which accounts for 88% of the time in this
       function. (This all eventually winds up in
       nsMsgMessageDataSource::createMessageNode.)

  - 25% of the time (63msec) is spent in five calls to
    PresShell::ProcessReflowCommands().

  - 13% of the time (33msec) is spent in 10 calls to
    nsWindow::OnPaint()

  - 7% of the time (18msec) is spent in two calls to
    nsXULElement::SetFocus().

  - 11% of the time is unaccounted for.