I got a bug report through Emacs Wiki (see
http://www.emacswiki.org/cgi-bin/wiki/NxhtmlMode) saying that Emacs
hangs when a large javascript file is opened. I tested and, yes, it
hangs when I try to scroll down a number of times.
I have attached the javascript.el that I have used. (This is the one
that has been considered for inclusion in Emacs.)
To see this do
emacs -Q
C-x C-f javascript.el
M-x eval-buffer
C-x C-f my-large-javascript-file.js
M-x javascript-mode
and then repeatedly press page down to scroll down. (Emacs will hang
completely and use all CPU power available.)
In GNU Emacs 23.0.60.1 (i386-mingw-nt5.1.2600)
of 2008-03-10
Note: I do not know which Emacs version jim-jam who told about the
problem uses, but it must be at least Emacs 22.