Very long lines in shell-mode

[Romain Francoise]

We recently fixed a similar issue in sgml-mode so we might want to have
a look at this one, it's been around for ever: very very long lines in
shell-mode cause Emacs to slow down considerably, eating CPU constantly.

For example, try:

  emacs -Q -f shell
  perl -e 'print "a" x 2000000; print "\n"'

This is probably due to the font-lock keywords set up by shell mode.
Unfortunately, they probably can't be anchored properly.  (And they're
very useful, so we can't just get rid of them...)

(This is not a regression compared to Emacs 21.)

-- 
Romain Francoise <address@hidden> | The sea! the sea! the open
it's a miracle -- http://orebokech.com/ | sea! The blue, the fresh, the
                                        | ever free! --Bryan W. Procter