Disable cache, enable normal lookup. Assume prefetch_related.
Method to precache translations in queryset.
Test optimization get_translations_queryset.
Moved query optimization to custom Manager/QS.
Removed custom chaining of prefetches.

Docs: "Chaining prefetch_related calls will 
accumulate the lookups that are prefetched."
Created separate filter for translated objects.

It turns out language filtering of related objects
is not propagated with prefetch_related.

Leads:
* https://code.djangoproject.com/ticket/17001
* https://pypi.python.org/pypi/django-prefetch