[OS X Emacs] Slow vertical split windows viewing same buffer in Aquamacs 1.6

Jose Figueroa-O'Farrill j.m.figueroa at ed.ac.uk
Wed Jan 21 17:29:51 EST 2009

>>>>> "David" == David Reitter <david.reitter at gmail.com> writes:

David> On 20 Jan 2009, at 22:54, Drew Hess wrote:
>> I'm seeing a performance regression in Aquamacs 1.6. Open a file
>> with 50+ lines in it. (I've tried text, elisp, Lisp and Scheme files
>> and all exhibit the same problem.) Make a vertical split window with
>> C-x 3. Make sure the 2nd window is displaying the same buffer as the
>> first. Now move around the file with C-p, C-n, C-f, etc.; try holding
>> one of the keys down until keyboard auto-repeat kicks in, for
>> example. On my machine, performance is noticeably sluggish when I do
>> this. Each additional vertical window displaying the same buffer
>> impacts the performance more negatively, When displaying a different
>> buffer in each window, however, the performance seems to be fine.
>> When I create horizontal split windows and display the same buffer in
>> each, I don't notice any performance hit, unless there's also at least
>> one vertical split displaying that same buffer.

David> I don't see it with vertical splits, but whenever SLIME is loaded.   
David> (That said, it may still be a problem specific to Aquamacs.)

David> Does this:

David> (setq redisplay-preemption-period nil)

David> make the jumpiness go away for you?

I can reproduce the behaviour reported by Drew in a LaTeX buffer.
Holding down C-n, the cursor goes down about 10 lines and then freezes
until I release C-n.  Doing as David suggests, solves the problem;
although it's a little jumpy.  This, however, I expect from my ageing

Cheers, José

Prof José M Figueroa-O'Farrill  | Phone: +44 (0) 131 6505066
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