bug#14786: 24.3.50; `field-end' is now very slow

[Drew Adams]

I'm not very good at measuring processing time.  If you need more info
about that then someone will need to remind me what functions to use for
measuring.

Here's what I see:

I put the cursor on, say, the first file or dir name in a large Dired
buffer (1860 lines).  I do `M-: (field-end nil)'.

In Emacs 22, 23, and even 24.3, the result appears immediately - no
perceptible delay.  In recent Emacs 24 (e.g., this build), the result
appears after several seconds - 3 to 4 sec.

This is a really noticeable difference.  It makes certain interactive
interactions nearly unusable.  Can something be done about this, or
is it perhaps an inevitable consequence of some feature that has been
added recently?

In GNU Emacs 24.3.50.1 (i686-pc-mingw32)
 of 2013-07-01 on LEG570
Bzr revision: 113246 lekktu@gmail.com-20130701165437-ea20s94hqwp3ttaj
Windowing system distributor `Microsoft Corp.', version 6.1.7601
Configured using:
 `configure --prefix=/c/usr --enable-checking CFLAGS='-O0 -g3'
 CPPFLAGS='-DGLYPH_DEBUG=1 -I/c/usr/include''