utf8::SWASHNEW

I just did a profiling on one of my programs, and it turns out it 
spends most of its time in utf8::SWASHNEW. In second place is one of my 
own functions, and in third place comes utf8::SWASHGET. What do 
SWASHNEW and SWASHGET do ? (in layman's terms-- I browsed the source 
but it gave me a headache). Is this a price to pay when using Perl 
unicode strings?
--
Eric Cholet