Are you sure you're on Ivy? Because 0710-avx is an mtune build while 0712v2 will only work on Ivy Bridge cpus.
Weird. I'm getting 50-100 higher PPS on your Sandy+Ivy V2 build than your Ivy only V2 build? Either way they are like the V2 Rockets of QT clients right now!
People need to donate to anonppcoin. He (assuming) put a lot of hard work into building.
There's several benchmarks on
www.phoronix.com on newer versions of gcc with ivy bridge support bench-marked against older versions. From my own experience Gcc4.8 with core-avx-i was a performace loss regardless of the software it compiled compained too 4.6 with corei7-avx, I can only speak for Linux on that account, as always your mileage may vary.