Re: The Emacs master is much slower than the emacs-27 branch.

[Gregory Heytings]

> > > > I bisected this, and the origin of the regression is commit 
> > > > 365dad197bac5deec9244fd9c189d23c46c99b31, which changes the default 
> > > > to "use 'static' instead of 'extern inline' [in C headers] because 
> > > > 'static' typically has better performance for Emacs".  With -Og or 
> > > > -O0, the benchmark takes 67 seconds, with -O1 or above (-O2 is the 
> > > > default) it takes 25 seconds.
> > >
> > > Thanks, then I think there''s no issue here, and we can stop wondering 
> > > about the difference in performance.
> >
> > There's no issue indeed, but it might make sense to merge commit 
> > b9b32074cecb0e0d20cf527eadacbb0b7f5cced9 into emacs-27.
>
> No, because emacs-27 only receives bugfixes at this time, and safe ones 
> at that.

Well, commit b9b32074cecb0e0d20cf527eadacbb0b7f5cced9 only changes 
'#define EXTERN_INLINE static' into '#define EXTERN_INLINE static inline', 
which seems pretty safe.  That being said, it's not critical, given that 
it only improves compilation with -Og.