CodeIgniter 3 only connect to database if theres queries to run?

I'm using CI3 and I noticed that every time that I enter to any Controller a connection to the database is made even if is not needed.

I used the Profiler ( $this->output->enable_profiler(TRUE); ) to see the performance and when I remove the database library from the autoload.php the pages that don't use any queries loads a lot faster. I've read the Docs but don't see any related to connect to the database only when a query is needed, for the moment I'm only importing the ( $this->load->database(); ) in each model instead of importing it in the autoloader and loading the models only when needed.
Is there any easier option to this behaviour with the Database Library?

Thanks.