Re: Reliable after-change-functions (via: Using incremental parsing in Emacs)

[Richard Copley]

Here, an -Og build takes about 2.5 times as long as an -O2 build to
execute either of the two benchmarks. That's a relative decrease of
60% in elapsed time, for -O2 relative to -Og.

I built Emacs in 4 separate clean worktrees of the master branch
(f71afd600a). The build commands were identical except for the
optimization flag. For each test I (twice) started "emacs -Q" and did
either [1] or [2]:

[1] M-: (benchmark 1 '(progn (find-file "src/xdisp.c")))
[2] M-: (benchmark 1 '(progn (find-file "src/xdisp.c") (sit-for 0)))

The elapsed time reported was:

without sit-for:
-O0: 1.027754s, 1.031642s
-Og: 1.295515s, 1.277441s
-O1: 0.629743s, 0.629870s
-O2: 0.513139s, 0.511230s

with sit-for:
-O0: 1.079090s, 1.068118s
-Og: 1.347256s, 1.337780s
-O1: 0.661679s, 0.664470s
-O2: 0.533649s, 0.533949s

(My only comment on the fact that -Og appears to be about 20% or 25%
worse than -O0 is that it's not a typo.)