Re: Font-lock in COMINT modes

[Stefan Monnier]

>> I listed in FOR-RELEASE that this case is slow:
>> 
>> You must have gotten that impression from Stefan's 12/08 message:
>> 
>> if [font-lock-defaults ] is nil font-lock-mode-internal is not
>> activated at all.  AFAIK nil and (nil t) are equivalent (i.e. don't
>> highlight anything), except that (nil t) takes a lot more CPU to do
>> nothing (it runs all the font-lock-foo-function hooks, enables
>> jit-lock so as to do nothing just-in-time rather than eagerly,
>> checks where nothing needs to be done, rounds up to a whole number
>> of lines the region upon which inaction is requested, checks if
>> there's a multiline entity and extends the region even more, so that
>> nothing is done in a multiline way, ...).
>> 
>> Even though it is true that font lock jumps through more hoops with
>> (nil t), there is no evidence that this slowdown affects the user.
>> 
>> 
>> Could you check and see?

> I haven't been able to observe any slowdown when font-lock-defaults is
> (nil t).  Not surprising, since I don't notice any slowdown when
> font-lock-defaults is (something t), i.e. normal font-lock situations!

> Maybe someone running on a 486 can observe a difference, who knows.

Indeed, the "slowdown" should be completely and absolutely neligible, even
on a 16MHz 386sx.


        Stefan