Whether to use Stored Procedure of Active Record Pattern in CodeIgniter?

Question

Hello,

I learnt that Stored procedures should always be favored over writing direct queries in code (Becaue our database engine caches the execution plan). But, in CodeIgniter i see a new concept of Active Record pattern. Is this execution plan cached in Active Record or every time the database engine has to parse the query? If it is parsed everytime, then how can i optimise my database access calls? I also don't see any way to call stored procedures from CodeIgniter's database core library.

Thanks in advance :)