Active Records Performance vs Raw Queries

The pure CodeIgniter has no ORM-implementation, neither "Active Record", nor "Datamapper" kinds.

A query builder is what CodeIgniter uses, the former name "active record" was not precise. And this query builder simply helps in generation of SQL statements and properly escaping inside them. It is quite fast, the performance impact is negligent. Use it with preference over the raw SQL, the syntax is beautiful and expressive, and the chance of you write some insecure queries gets lower. Even it gives you some abstraction of the SQL-server type, although 100% is not the goal.

The CodeIgniter's query builder has nothing to do with the "To ORM or not?" debates, it is not a ORM-kind of feature.