Re: open large file with C code: is it realy should be so slow?

[Alan Mackenzie]

Hi, Dave!

On Mon, Dec 01, 2008 at 01:01:08PM +0300, Dave Milter wrote:
> I have problem with emacs responsibility,
> I work with large enough C header files,
> and when I want to scroll it using mouse's wheel or
> page (up|down) keys emacs stop react on any keys, like (ctrl+g),
> and eats 100% of CPU's time during long period,
> I wonder is this a bug, or expected behaviour?

It's a bug.

Although C Mode works "properly" here, it doesn't seem to be tuned very
well for files like this one (At91SAM9253_inc.h), which contain a lot of
#defines and comments and nothing else.

The only workaround I can suggest at the moment is to turn font-locking
off in these buffers.  This is clearly unsatisfactory.  Sorry.

> My cpu frequnce is 2200.000MHz.

> elp results are:

[ Thanks for these! ]

> Version:

> GNU Emacs 22.3.1 (i686-pc-linux-gnu, GTK+ Version 2.12.8)


> I tried Visual C++ 6.0 under wine,
> and gvim, and they works without any delays,
> highlight syntax and allow scrolling.

> If somebody wnat reproduce this behaviour,
> here is link to source code with which I working:
> http://www.atmel.com/dyn/resources/prod_documents/AT91Bootstrap1.10.zip
> there are files in it like
> include/AT91SAM9263_inc.h
> it contains around 4000 lines of code,
> most of which is comments or #define

I will try to fix this bug, though this could be quite difficult and take
some time.  Thanks very much indeed for taking the trouble to report it. 

-- 
Alan Mackenzie (Nuremberg, Germany).