The text object is probably your best bet for for the asian languages.
Regarding performance impact, basically it's not as good, but should be negligible unless you're doing something crazy. Try to avoid updating many different font objects every tick (such as displaying the contents of a big array in real time). Update only when necessary (such as when a value actually changes), and use less instances of text objects at a time wherever possible.
If your game isn't text heavy, it's not unheard of to simply bake the text into your ui sprites, for limited multi-language support, for better control over the look and feel of your game. You can also use a combination of these techniques if you want, between dedicated sprites and text objects.