bug#11657: 24.1.50; Byte compiler is a lot slower now, when run interpreted

[Eli Zaretskii]

> From: Stefan Monnier <monnier@iro.umontreal.ca>
> Cc: 11657@debbugs.gnu.org
> Date: Sat, 09 Jun 2012 21:24:43 -0400
> 
> One potential source of slowness is the use of `pcase' in macroexp.el:
> when byte-compiled, this is not a problem since it's all macroexpanded
> away into reasonably efficient code.  But when interpreted, the `pcase'
> macro might get re-expanded over and over, and it's a macro that's
> costly to expand (because it has to work fairly hard in order to get
> this reasonably efficient code).  pcase.el uses a hash-table to memoize
> the recent expansions, but if for some reason this memoization fails and
> the pcase macro gets re-expanded all the time, then an 8-fold slowdown
> would not surprise me.

Is there any way I can help you look into this?