[Simon Meisinger]

Actually, I think the problem that Hammond had was that he wasn't going fast enough - couldn't get heat into the tires and/or make appropriate use of the extensive F1 aerodynamic package, thus making the car hard to drive (because he was going too slow).

He was going too slow for how fast he wanted to go, even if that sounds strange

You can go slow to semi-fast in an F1 car or superfast. You can't just go something inbetween as you need warm tires and a enough downforce for that. I think Hammond also tried to go very fast in very tight corners, which might even be a challenge for some professional racers.