Well, I'm not allowed to pass the pitlane at 300 kph for applying drive-thru penalty if that is you want to be.
However, you may still approaching at high speed, but the car will automatically apply the brake. This is from the game behaviour.
I've already found a new method to restrict player approaching the pitlane entry at high speed. Hope this is available at next release.
For the problem you mentioned in this forum, unfortunately, there is no solution for now to avoid the car a little bit slower when approaching their own paddock. But I'm still trying to find it. Don't worry be happy.
Ch88rs,
Madman