FTS Tokenization filters normalizer-icu vs lowercase

Hi,

I'm trying to setup fts-flatcurve with tokenization.

What are the differences/benefits with "fts_filters = normalizer-icu" vs "fts_filters = lowercase"?

Reading the Doc I found about normalizer-icu "This is potentially very resource intensive." and about lowercase "Supports UTF8, when compiled with libicu".

So, using lowercase is almost the same that normalizer-icu but faster?

FYI

for using fts-flatcurve with dovecot RPM packages from repo.dovecot.org you have to rebuild with --with-icu --with-stemmer --with-textcat and related library.

Thanks

-- Alessio Cecchi Postmaster @ http://www.qboxmail.it https://www.linkedin.com/in/alessice