Performance concerns

[sveetch]

Is your feature request related to a problem? Please describe.
There is currently no real issues with SQL queries, however we currently don't have any performance metrics of SQL operations performed in Lotus.

Article/Category should be very efficient since they have been built correctly, however the introduction of tags add something more and i'm wondering how it could grow executed queries (there is not select_related of prefetch_related in query, so listing article and displays their tags could be huge).

Describe the solution you'd like
Add new tests like in "tests/060_benchmark/" to check for templatetags and view operations and check how much queries they did and assert them.

Then it can be helpful to improve some operations with little adjustments.

[sveetch]

Before to start test, we may first localy install django-debug-toolbar to inspect what is going on and find some adjustments.