Re: comint-last-output-overlay -- overlapping overlays

[Alex Schroeder]

Miles Bader <address@hidden> writes:

> Alex Schroeder <address@hidden> writes:
>> If you have ever used ansi-color.el with Emacs 20, you will have
>> noticed that "ls /dev" can bring Emacs to a standstill.  The reason is
>> simple: overlapping overlays are a real Emacs display killer.
>
> I've noticed some problems when lots of overlays overlap, but not if
> it's just a few.
>
> What exactly is the overlay configuration that's causing problems?

I just found that the problem doesn't happen using emacs -q!  I am
very surprised.  After some investigation, it seems that the culprit
is (global-font-lock-mode 1).

I've put the following three lines in tmp/test.el:

(ansi-color-for-comint-mode-on)
(global-font-lock-mode 1)
(shell)

I start Emacs as follows:

emacs -q -l tmp/test.el

At the shell prompt, type:

ls /dev

My /dev contains more than 1300 files, all of the will be colored in
my current setup.  Now, with global-font-lock-mode enabled, ls /dev
takes significantly longer to complete.

Alex.
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