ORMs

[eluser]ClaudioX[/eluser]
Hi all, I would like to adopt an ORM, we all know the benefits (maintenance, organization and speed), however, in some articles talk the performance worsens. From what size of projects, it is noticeable? (to be a problem?)? and its is really true?

And which libraries of ORM for CI is more mature? (please, i dont like this sound bad)

Really thanks for the help, that has been important to me. Thanks all!