Best pratice splitting up language files?

Hi
just started learning the zf a couple of weeks ago, i reached the zend_translate witch i have a few "best pratice" questions about.

if i were to build a multilanguage webpage, and lets say i choose the simple array adapter.
I dont know much about how the php-engine works in the backscene but my guess would be loading a language file containing all my language strings for all my views / validators etc for each request, would be bad pratice ? wouldnt it be better to somehow split the language file into controller -specific files so that each controller had a language file of its own?..

The only info i could find was if my language file gets too big i should go for another adapter? but changing to another adapter wouldnt change the fact that i was loading tons of language string i wouldnt need for the request?.

im sure there is a logic explaination, but i cant seem to find it in eny of the guides / articles on the net.

- Mads Lee Jensen