That's for the Hardline beta, but I would think it'd work for the release as well. I don't own the game myself, so I have no way of verifying whether it works or not. Just make sure that if it asks you if you want to overwrite anything to make a copy of the original before you do so.
First I would make sure that your display drivers are up to date, because with a game that new if your drivers are even a little out of date it can seriously impact performance. Then make sure the game is updated. If that's not the issue then the game might still be having optimization issues and you might have to live with it until they fix it.
That's for the Hardline beta, but I would think it'd work for the release as well. I don't own the game myself, so I have no way of verifying whether it works or not. Just make sure that if it asks you if you want to overwrite anything to make a copy of the original before you do so.