Subject: Re: bug#16526: 24.3.50; scroll-conservatively & c-mode regression

From: Eli Zaretskii <[email-masked]>
Date: Sun, 02 Feb 2014 20:07:25 +0200

> Date: Sun, 2 Feb 2014 17:40:50 +0000
> Cc: martin rudalics <[email-masked]>, [email-masked]
> From: Alan Mackenzie <[email-masked]>
> 
> > Perhaps Alan could explain why the CC Mode fontification takes such a
> > long time for buffer position 948757.
> 
> No, sorry I can't explain it.  Except that CC Mode will be scanning
> forward through the entire buffer once (hopefully only once) to get the
> "parse state" near EOB.

Why can't it start from a position outside any function instead?

> On a normally optimised 24.3 build, M-x goto-char 948757 is taking me a
> little over a second.  This is in a GUI frame in X Windows, maximised by
> clicking on the maximise button at the top right of the frame.
> 
> On my non-optimised 24.3.50 build with tracing built in, the same action,
> M-x goto-char 948757 takes 9 seconds.  In a non-maximised frame it takes
> 8 seconds.  In this build, M-> takes ~2 seconds regardless of whether the
> frame is maximised or not.  I can't explain this difference.

These times are consistent with what I see.

> I've committed my patch.  I hope it clears up the bug (which I haven't
> yet closed) more or less satisfactorally.

Thanks.