X 3.
By "bad" I would assume you still mean somewhat reasonably drivable? Ie...not so stupid-bad that you can hardly putt down the street without running over mail-boxes.
If the suspension is set-up lame, it will severely affect the driver no matter what the skill level. Even a professional would have to constantly correcting, with probably very little margin for error. Hypothetically it may slow down Joe Average by 5 minutes on "course X." The professional might only be slowed down by 1 minute, 30 seconds, or even 10 seconds, but that is a lifetime in a racing event.
I've seen the Stig spin out multiple times in the same "supercar" that was set-up flawed and incorrectly at the factory. As he spun backwards through the grass it appeared to me that the suspension was affecting him a great deal.