bug#18522: 24.4.50; mapcar is very slow

[Eli Zaretskii]

> From: Peter Münster <pmlists@free.fr>
> Cc: Eli Zaretskii <eliz@gnu.org>,  larsi@gnus.org,  18522@debbugs.gnu.org
> Date: Sun, 21 Feb 2016 15:54:43 +0100
> 
> Sorry, I was wrong. The problem seems to be the binding of
> case-fold-search:
> 
> (defun my-parse-time-string-test ()
>   (let (case-fold-search)
>     t))
> 
> (let ((gc-cons-threshold most-positive-fixnum))
>   (benchmark-run 1
>     (dotimes (i 100000) (my-parse-time-string-test))))
> 
> Fast emacs: (0.054105733 0 0.0)
> Slow emacs: (1.754813882 0 0.0)

Does this happen only with this particular symbol, or binding any
symbol slows down?