Subject: Re: bug#18752: 24.3.94; Why is Cygwin Emacs 2x quicker than Windows Emacs?

From: Eli Zaretskii <[email-masked]>
Date: Sat, 18 Oct 2014 20:46:07 +0300

> Date: Sat, 18 Oct 2014 13:35:48 -0400
> From: Ken Brown <[email-masked]>
> CC: [email-masked], [email-masked]
> 
> On 10/18/2014 12:17 PM, Eli Zaretskii wrote:
> > Unoptimized builds make debugging easier, but are about 2 - 2.5 times
> > slower than optimized ones.  For that reason, the usual practice is to
> > produce unoptimized builds for snapshots and pretests, but optimized
> > ones for official releases.
> >
> > Latest GCC versions support a -Og optimization switch that gives you
> > the best of both worlds.
> 
> Do you happen to know how much of a performance difference there typically is 
> between -Og and -O2?

No; measurements welcome.

Personally, I'd be surprised to see more than a few percents of
difference for Emacs.