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

[Eli Zaretskii]

> Date: Fri, 4 Dec 2015 16:06:40 +0000
> From: Artur Malabarba <bruce.connor.am@gmail.com>
> Cc: Alan Mackenzie <acm@muc.de>, 22090@debbugs.gnu.org
> 
> > Thanks.  Is there any reasonably simple way of describing the
> > resulting limitations (i.e. what will NOT match) on the user manual
> > level?
> 
> Basically, 'a' will match similar characters (like '𝑎' and 'á') and
> their upper-case equivalents (like 'Á'). 'a' will NOT match characters
> similar to 'A' that don't have a lower-case equivalent (like '𝔸') in
> the unicode standard.

What about ligatures, or symbols like ℻?

Also, by "lower-case equivalent" do you mean a case mapping defined by
the UCD, or just by visual appearance?  An example of the latter would
be Ⓐ vs ⓐ.