bug#16731: 24.3.50; Latin small letter sharp s is not considered lower-case

[Stefan Monnier]

>> Doesn't sound too bad.  But it does beg the question: why check
>> (downcase (c) != c) at all, then?
> Because it's faster,

Is it?  Both lookups look like CHAR_TABLE_REF to me.

> and for most characters will do the job.

But we'll check the unicode table at least for more than half the
characters (i.e. for all the lowercase and non-case characters), so the
fast path can't give us more than a factor of 2 speed up anyway, and the
slow path is made slower by unnecessarily looking up the case table.

I guess what I mean is that without actual measurements it's not obvious
at all that speed is a good justification.


        Stefan