[webkit-reviews] review requested: [Bug 12833] REGRESSION: Selecting text in 6.6MB txt file is sluggish as of the Feb 19th nightly : [Attachment 13540] improve selection performance

[bugzilla-request-daemon at macosforge.org]

Antti Koivisto <koivisto at iki.fi> has asked  for review:
Bug 12833: REGRESSION: Selecting text in 6.6MB txt file is sluggish as of the
Feb 19th nightly
http://bugs.webkit.org/show_bug.cgi?id=12833

Attachment 13540: improve selection performance
http://bugs.webkit.org/attachment.cgi?id=13540&action=edit

------- Additional Comments from Antti Koivisto <koivisto at iki.fi>
This patch improved time it takes to do SelectionController::setSelection() at
the end of http://dscoder.com/test.txt from 200ms range to around 20ms.
Unfortunately it is still more sluggish than Tiger WebKit but at least it is
sort-of usable (selection is quite a bit faster in release build than debug
build too).

Basic idea is to do way less line box traversing than before. It is also
possible that some of the stuff editing code is doing during selections is
actually unnecessary, I can't really tell. This patch doesn't change anything
in that respect.