The new 2012 i7-3667U MacBook Air's are incorrectly clocked in Windows under Boot Camp. Rather than running at a x20 multiplier (2GHz) they run at x19 (1.9GHz) and never go into Turbo Mode and rarely drop down to lower multipliers/clock-speeds. As a result under Windows they are slower than the much cheaper i5 and also sip more energy due to not dropping down to lower speeds.
More here: http://forums.macrumors.com/showthread.php?t=1394206 and here: https://discussions.apple.com/thread/4035733?start=0&tstart=0