Re: Speed of all-completions

[Stefan Monnier <monnier@iro.umontreal.ca>]

Barely 6 years ago, Jesper Harder <harder@ifa.au.dk> wrote:
> I use icomplete-mode and I've noticed that it feels more sluggish in
> cvs Emacs than in Emacs 21.3.
> Profiling shows that the bulk of the time is spent in
> `all-completions', so I tried to benchmark it with this example:
> (defmacro time (form)
>   `(let ((t1 (float-time)))
>     ,form
>     (- (float-time) t1)))
> (let ((oba (make-vector 255 0)))
>   (dotimes (i 10000)
>     (intern (format "f%i" i) oba))
>   (time
>    (all-completions "f" oba)))
> The time used was:
>   cvs Emacs:   0.16448211669921875
>   Emacs 21.3:  0.01507115364074707
> i.e. `all-completions' is roughly an order of magnitude slower in cvs
> Emacs.

I cannot reproduce it now.  I tried it with `emacs21', `emacs22', and
`emacs23' (under Debian testing, and adding a 0 to the number of
iterations of your test), and I do see that Emacs is getting slower, the
difference is not nearly as large, changing from 0.05s to
0.06s, basically.


        Stefan "you can always count on a prompt answer"