Raymond Toy <toy(a)rtp.ericsson.se&gt; writes in xemacs-beta(a)xemacs.org: Check the *Message-Log* buffer for messages. If you are running up against the soft font-lock limit, there will be a message telling you about it. What is your value of font-lock-maximum size? Size does matter. I crank the size up in my .emacs, I don't know what the default is. It's small enough to be annoying (IMO). C-h v font-lock-maximum-size `font-lock-maximum-size' is a variable declared in Lisp. -- loaded from "font-lock" Value: 1024000 Documentation: *If non-nil, the maximum size for buffers for fontifying. Only buffers less than this can be fontified when Font Lock mode is turned on. If nil, means size is irrelevant. If a list, each element should be a cons pair of the form (MAJOR-MODE . SIZE), where MAJOR-MODE is a symbol or t (meaning the default). For example: ((c++-mode . 256000) (c-mode . 256000) (rmail-mode . 1048576)) means that the maximum size is 250K for buffers in `c++-mode' or `c-mode', one megabyte for buffers in `rmail-mode', and size is irrelevant otherwise.