Re: Scrolling xdisp.c. Room for optimisation in syntax.c/CC Mode.

[Ulrich Mueller]

>>>>> On Mon, 20 Oct 2014, Stefan Monnier wrote:

> So the performance differences could also come from CC-mode rather
> than from Emacs's C code.

Indeed. If I run all tests with CC Mode 5.32.5 then the large
difference between Emacs 23.4 and 24.3 disappears:

   no-odd-xdisp.c:
   23.4:      415 scrolls, total time = 45.01029920578003s.
   24.3:      415 scrolls, total time = 43.775553941726685s.

   xdisp.c:
   23.4:      415 scrolls, total time = 48.97985076904297s.
   24.3:      415 scrolls, total time = 47.60138463973999s.

My previous numbers using the CC Mode version bundled with Emacs
(i.e., 5.31.8 and 5.32.4 for Emacs 23.4 and 24.3, respectively) were:

   no-odd-xdisp.c:
   23.4:      415 scrolls, total time = 14.116178750991821s.
   24.3:      415 scrolls, total time = 45.48526978492737s.

   xdisp.c:
   23.4:      415 scrolls, total time = 14.051368474960327s.
   24.3:      415 scrolls, total time = 50.858959674835205s.

Again, tests done with emacs -Q -nw in an xterm, 80 columns times
80 lines.

Ulrich