Globalize, the plugin that Motiro uses for internacionalization, stores text on a database (with no caching by default). Maybe this is making the responses slower that they need to be.

One of the possible solutions (if this is really a problem, of course) is to put a caching mechanism in place. Translations could be stored on faster memory once they get loaded from the database. This can be done using memcached ou another similar solution.

Another solution is to avoid using Globalize completely. It could be changed for another pre-packaged Ruby/Rails solution or a home made one. Translation strings can be stored in-memory when the application server is started (or on the first request). After that all queries would hit memory directly. This solution has the hidden bonus advantage of reducing the installation time.

There is a comparison of some other solutions for translation on the Rails' wiki.