Re: Mysterious fontification/C++ context issue

[David Kastrup <dak@gnu.org>]

Alan Mackenzie <acm@muc.de> writes:

> With Martin Rudalics's optimisation to c-beginning-of-defun-raw, I
> don't feel that the slowness is too bad any more (though he does
> ;-).  In the extreme case xdisp.c, scrolling to EOB and M-v is
> mildly sluggish (about half a second), on my 5 year old Athlon 1.2
> GHz machine.  A typical new PC now is, say, 3 GHZ.  In the time
> Emacs 22 is the current release, a typical new PC will come to be
> around 20 GHz, and this slowness will not matter.

Please, arguments like that are just not acceptable.  If examples with
barely tolerable behavior can be come across easily, you can bet that
there will be normal use cases where the the behavior will be quite
intolerable.  And even on faster machines, editing should try avoiding
draining unnecessary CPU power: editing is by far the most important
application where you want to have a long battery life for laptops.

I am working with a 600MHz laptop, and my occasionally used desktop
system has a 233MHz processor.  The preview-latex
<URL:http://www.gnu.org/software/auctex/preview-latex.html> package
has been streamlined to operate well on such machines.  It would be
really a bad hoax if syntax highlighting (which does a lot less) would
make such machines unusable for editing with an up-to-date Emacs with
default settings.

When stuff becomes sluggish on a machine of _your_ power, that most
likely implies an O(n^2) or worse behavior.  And that means that it
does not take much of a change in the highlighted file to get
intolerable behavior on your machine or even better ones.

-- 
David Kastrup, Kriemhildstr. 15, 44793 Bochum