语言版本PHP Framework

I am currently developing a custom PHP framework for a website I am working on. It is a MVC(L) framework and I have most of it in place thus far. I am currently working on URL routing and next I will be looking at language versioning.

What I have is a database filled with data. Every word/sentence has an id, a key and a value for each language.

My website will be launched in several countries so it needs to scale on the number of languages.

So my question is: In your experience, what is the best approach for having a single code base with several languages?

1. Is it to query the database on each word?
2. Load all words from database for each page at one time?
3. To have some sort of file system created for look up, in order to not overload the database.

We are looking at 15.000 visits daily on each site, with each page having a possible number of words to translate over 100.

Has anyone had this challenge and solved it. What is the best approach? Are there any PHP libraries for this?

Best regards, Rasmus

For me the best approach would be to generate a static file of all your word for a language, and use this in production. Of course the static file would be generated automatically. You can also imagine caching it in a Memcache server of something similar. Avoid accessing the database.