The builders and builds should be cached in a file so we can avoid to retrieve them each time. The Builder and Build objects have already an asdict() method that serialize them in a dict and a fromdump alternate constructor to create the instance from the serialized data. We should only decide a format (pickle? json? shelve?) and implement the caching.

We will use sqlite.

this issue is done, isn't it?

Done, but the methods asdict() and fromdump() should be removed, probably.