bug#22090: Isearch is sluggish and eventually refuses further service with "[Too many words]".

[Eli Zaretskii]

> Date: Fri, 4 Dec 2015 15:16:23 +0000
> From: Artur Malabarba <bruce.connor.am@gmail.com>
> Cc: Alan Mackenzie <acm@muc.de>, 22090@debbugs.gnu.org
> 
> 30f3432 * lisp/character-fold.el: Remove special case-folding support
> 
> (character-fold-to-regexp): Remove special code for
> case-folding.  Char-fold search still respects the
> `case-fold-search' variable (i.e., f matches F).  This only
> removes the code that was added to ensure that f also matched
> all chars that F matched.  For instance, after this commit, f
> no longer matches 𝔽.

Thanks.  Is there any reasonably simple way of describing the
resulting limitations (i.e. what will NOT match) on the user manual
level?