The mirroring doesn't work. Having forced my iPad to do it via jailbreaking, it's clear the A4 chip isn't fast enough to do it for apps with any video or animation at all.
a) Apple is shipping, and loudly promoting, a feature that "doesn't work" because of a fundamental, immutable hardware deficiency.
b) The software implementation of an unsupported hack, used by an infinitesimal number of users, written by someone who is unpaid and not intimately familiar with the hardware stack and firmware, is inefficient.
