actually no. there is around a 30% difference from the HD4000 in the ulv cpus than from the standard voltage ones, they cant maintain the clocks, they oscilate, aside that the clocks are lower, sometimes this makes a good difference and in other times barely
While you are absolutely right and technically correct, I did not see these results.
On the other hand, the office Sony Z uses a standard CPU clocked roughly the same "Dual Core i5 / HD4000" and it performed much better than the rMBP 13" under bootcamp with the same drivers installed.
Lubbosfan Control was even used because I thought it might be a throttling issue.