this is one of 2 videos on whole youtube... you cant find more than 2 videos like this... back in 70's and 80's you could see it every lap... perhaps every corner... cheers!
So they were obviously not going as fast as they could have over the entire length of the race.
And since when have computers been taking over besides when they had traction control? Its not like the onboard telemetry and all the sensors control what the driver does with the throttle, brake, and steering. And just because they're not letting their rears let loose into the wind means they're not at the limit of adhesion.