Is this during the language change, or an aftereffect? If it's during, then the answer is that the game has a TON of text to translate. If it's after, it COULD be the game not being used to the new language. That's just a theory, however. I don't pretend to understand complex Java.
Confirmed for 1.8.3. This is annoying, because if you're standing on soul sand for example, the sky appears completely dark!