Cc-mode font-lock too slow with large file

Cc-mode font-lock too slow with large file

[kona.ming]

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I have a large c file,about 10000 lines. I can't scroll it after open, has 2 or 3 seconds lag. The font-lock-maxium-decoration is t, set it to 2 will better but still lag.
How to making emacs working on the file?


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Re: Cc-mode font-lock too slow with large file

[Alan Mackenzie]

On Tue, Oct 15, 2013 at 05:27:14PM +0800, kona.ming wrote:
> I have a large c file,about 10000 lines. I can't scroll it after open,
> has 2 or 3 seconds lag. The font-lock-maxium-decoration is t, set it to
> 2 will better but still lag.  How to making emacs working on the file?

This is not usual in C files.  For example, xdisp.c (part of Emacs) is
~30,000 lines long, but scrolls reasonably fast.  It may be that there's
something unusual about your file which is making C Mode slow - something
like a very large macro, or a very large enum.

Firstly, could you please tell us what version of Emacs and CC Mode
you're using.  (M-x emacs-version and M-x c-version).

Is the lag as bad if you start Emacs as emacs -Q?

Would it be possible for you to send me the file?  If so, please send it
to <acm@muc.de>, and tell me anything I need to do to make it slow.  Then
I can investigate the problem directly.

> 从三星移动设备发送

-- 
Alan Mackenzie (Nuremberg, Germany).