no way a slide like that cause one second. look at Heikki's Q2 lap in silverstone when he had a similiar slide out of luffield, even on a F1 car it cost no more than 2 to 3 tenths.
and it power oversteered out of corners often??? sorry I only spot one or two that really could count as power oversteer beyond traction limit. it's a rear wheel drive car with a lot of hp it is logical it ain't very tidy, but it was almost never out of balance or even make a tire squeal.
the GTR of course is much more tidy because it is AWD and setup to be understeery on power, as most AWD supercar does, there's very little chance a driver and break the traction. even the general balance is more understeery than the ZR1. The ZR1 is more about point and squirt, I'll say it's definitely not untidy considering the amount of power it has. .