Makefile mode font-lock inefficiency

[David Abrahams]

Recent builds of emacs seem to almost "hang" whenever I visit a
makefile.  Take, for example, lisp/makefile.in in this project.  I
have to kill font lock with C-g and change to text mode in order to
look at it.  I traced the problem down to the fact that I set
font-lock-support-mode in my .emacs

I was setting font-lock-support-mode to lazy-lock-mode, but even
fast-lock-mode causes the problem.  I now notice that these packages
are obsolete, but only preparing this bug report was enough to get me
to notice that.  I think this is a usability bug, but I don't know how
it should be addressed.

-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com