Complex sentence: To increase performance, a server will typically remember (cache) these translations for a certain amount of time, so that, if it receives another request for the same translation, it can reply without having to ask the other server again.
Split into simpler sentences: To increase performance, a server will typically remember (cache) these translations for a certain amount of time. Now, if it receives another request for the same translation, it can reply without needing to ask the other server again.