ooooooooo another DMF victim. You not only need a clutch, you need a new flywheel as well. Dual Mass flywheels are good for only one clutch unless you've only got like 20k miles on that one clutch. Once you get it apart, you should verify if you have an aftermarket one piece flywheel or a DMF. If you do have to replace the flywheel, you also need new bolts. I have personally seen the effect of not replacing the bolts when replacing the flywheel- and it's not pretty. You can damage a lot more than you think if the flywheel comes loose from the crank.
What exactly is it doing? You say it's slow when it starts off? I don't comprehend. When the clutch goes out, the engine will rev freely in gear and not grab. A sticky slave cylinder will do that as well, and so will a loose pressure plate. Replacing a clutch isn't super duper simple in this car, so I just want you to be sure that he's telling you the right thing.