Its easy to see that A7 is way faster than A6, just run the same project in A7 and A6.

But when you dont want to use AABB then you should compile your level in A7 mesh mode. A6 levels with OBB are slower than A7 levels with OBB. This has nothing to do with A6 and A7, it seems you were just confusing AABB and OBB.