Original PR description

name_get method is a critical one to performance issues since that is used in all views for m2* fields.

Then avoid get all fields if the view just is showing one field.
But if previously the cache is prefetch was filled then re-use it if not then don't read all other fields.

Avoid access to `if name in self._fields: self._fields[name]` 2 times
Better use `field_name = self._fields.get(name) if field_name` used just one time.