[OS X TeX] Extremely slow editing behavior with TeXShop

[James Crippen]

I'm using TeXShop 2.15 (downloaded from Richard Koch's personal site)
on Mac OS X 10.5.3, on a MacBook Pro.

The problem I'm having is that the TeXShop editor window becomes
unreasonably slow when working on long documents. I broke my Tlingit
grammar (http://www2.hawaii.edu/~crippen/papers/tlingit-gram.pdf) into
separate files for each chapter to try and help with this.
Nevertheless, the verb chapter is still 289 kB in size, with 5920
lines, 37k words, and 279k Unicode characters. This doesn't happen
with smaller documents in TeXShop. Smultron and TextEdit don't have a
problem with files this large, it's just TeXShop which is misbehaving.

I have a CPU meter running which shows that every keypress causes
significant CPU usage, on the order of 30% or more, sometimes up to
50% with rapid typing. The response time is so slow that I can usually
type five or six letters before they appear on the screen in a short
burst. There's a definite lag of nearly a second from when I type a
single letter and when it appears on screen. Quitting and restarting
TeXShop doesn't fix the problem, it reoccurs only a few keystrokes
after I start editing in a new session. It doesn't matter what font I
use for the editor window, although I usually use Lucida Grande at 12
pt.

I've tried fiddling with the ReleaseDocumentClasses preference, and
with the ReleaseDocumentOnLeopard preference. None of the possible
combinations of settings for either of these has any appreciable
effect. I thought that it might be syntax highlighting, so I turned
that off, but it didn't help. I tried to turn off paren matching, but
this apparently can't be disabled despite the setting in the
preference pane.

I'd be willing to do a trace of the application while I'm working on
this to help find the culprit for slowness, but I'm not knowledgeable
enough about Objective C and Cocoa programming to fix the problem
myself.

Help!
James Crippen