529222 - Paint is slow on Windows Mobile

Status: RESOLVED WONTFIX

(Firefox for Android Graveyard :: General, defect)

Description

[Alex Pakhotin (:alexp)]

Attachment: Timings

The slowdowns in the Paint functions seem to be due to the files loading.
The log with timings is attached. A section from the log for one OnPaint call is copied here: http://pastebin.mozilla.org/684303

Every time when a new nsImageLoader is created, the nsCSSRendering::PaintBackground function takes up to 100 ms compared to normal 3-4 ms. Once the file used for rendering is loaded and cached, further timings come back to normal.

Similar slowdowns happen for many elements, the background is probably just one of the most noticeable.

Comment 1

[Doug Turner (:dougt)]

do you know what the image is being loaded and if it has a alpha channel set?

Comment 2

[Alex Pakhotin (:alexp)]

I believe the slowdown is just because of the fact of file loading itself, it is not related to a specific image. File system on WinMo is just too slow.

Comment 3

[Mark Finkle (:mfinkle) (use needinfo?)]

Is it being loaded from a JAR file? We should have mmap working for JAR files now.

Comment 4

[Alex Pakhotin (:alexp)]

The measurements were made three weeks ago. The situation may have changed since then - needs confirmation.

Comment 5

[Doug Turner (:dougt)]

This year we mothballed windows mobile development.  See:

  http://blog.pavlov.net/2010/03/22/stopping-development-for-windows-mobile/

Marking bugs in the windows mobile / windows ce bucket as WONTFIX.