Re: [Bug-gnu-emacs] Frantic window manager

[Gerd Moellmann]

John Abbott <abbott@poly.dima.unige.it> writes:

> VERBAL DESCRIPTION:
> According to the "top" program when executing the commands below
> graphical emacs causes my window manager (twm) and X server to consume
> large amounts of CPU while the repeated "C-x e" macro is running.
> The problem does not occur using "emacs -nw" inside an xterm.
> 
> TO REPRODUCE PROBLEM:
> Create a file as follows (Unix/Linux shell commands):
> yes "aaaaaa: bbbbbb" | head -100000 > file
> 
> In (graphical) emacs visit this file (I used C-x C-f) and
> define a keyboard macro as follows
> C-x (
> M-z :
> C-n
> C-x )
> 
> In another window start "top" running.
> Now execute the macro 99999 times:
> M-99999 C-x e
> 
> Observe that "top" reports that emacs, the window manager and the X
> server are all using a lot of CPU.  The same operations under a
> non-graphical emacs (started with "emacs -nw" in an xterm) result
> in only emacs using CPU, and moreover the total CPU time needed to
> complete the 99999 applications of the macro is considerably less
> than with a graphical emacs.

Thanks for the report, John.

The reason for this is that, in your test case, the zapped string is
repeatedly put in an X cut buffer, which involves quite some X traffic.
I don't know how to avoid that traffic in the general case.

For your specific case, I'd suggest to use M-x replace-regexp, or
write a small Lisp function.