Re: emacs-26 eec71eb: Speed up replace-buffer-contents

[Paul Eggert]

Eli Zaretskii wrote:
> Profiling shows that 'diag' takes 32% of the CPU time, and
> buffer_chars_equal takes another 45%.  So any significant gains will
> be in buffer_chars_equal, I think.

Yes, that was what my intuition was pointing at as well. Among other things, we 
can fix the quit problem without having a rbc_quitcounter variable.

I typically measure effectiveness of performance tweaks when using the 
'configure' default of CFLAGS='-g3 -O2', since that's how it's typically built 
downstream. If this particular problem is all about CFLAGS=-O0 please let me 
know, as I guess I can look at that too (but would rather not).