"As with any good actioner, the race scenes are made more exciting after the narrative has been established. Ron Howard wisely saves the big-time racing mayhem until he's established the players and the stakes. When the inevitable F1 madness takes place, there is significant weight behind the tire squeals. Combined with Howard's expert direction, the payoff is blistering."
I would also add that this is probably the best racing film ever made exactly for the reason you stated above. Nearly all racing films from Grand Prix, to LeMans, to even Talladega Nights: The Ballad of Ricky Bobby, start with racing scenes and later try to establish characters. All these films lose momentum while they later try to establish the characters and hope the audience will invest in these characters while waiting for the next action sequence starts.