I will try to shed some light on this problem: When you install eZ publish with a translation ( other than eng-GB ) it will need to parse the translation file, which is an approx 200K XML file. The file is in unicode and needs to be converted to your locale. If you don't have mbstring compiled into PHP eZ publish needs to do the string conversion "manually" which is a very big overhead. This can cause processing which exceeds 30 seconds.
This is only done the _first_ time a new translation is accessed, is is then cached. If you compile PHP with mbstring this goes alot faster, but it's still an overhead the first time you access the translation.
