What is the affect of too much downforce on a Formula One car?

Question: What is the affect of too much downforce on a Formula One car?
- Keywords:
  car,
  downforce,
  formula 1
Asked by jamesat79 to Steve on 19 Jun 2013.
- Steven Gardner answered on 19 Jun 2013:
  
  Think you might be confusing me with Colin, but I’d guess that too much downforce means the car won’t travel fast enough on the straight, because it will stick to the road too well. Perhaps you could ask Colin and see if he agrees with me!

Question: What is the affect of too much downforce on a Formula One car?