3rd-party cross-platform UTF-8 support

[Changjian_Sun]

For cross-platform software (NT,Solaris,HP,AIX), the only 3rd-party unicode support
I found so far is IBM ICU.
It's a very good support for cross-platform software internationalization. However,
ICU internally uses UTF-16, For our application using UTF-8 as input and output,
I have to convert from UTF-8 to UTF-16, before calling ICU functions (such as ucol_strcoll() )

I'm worried about the performance overhead of this conversion.
Are there any other cross-platform 3rd party unicode supports with better UTF-8 handling ?
Thanks a lot.

-Changjian Sun