New serial kernels aren't speeding things up at 25q

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Petar Korponaić reports that 1.13.0 isn't improved with new serial kernel improvements.

For 25-qubit QFT,

qvm -S 61 seconds
qvm -S -c 27 seconds
qvm -S -c -O 3 12 seconds

Petar reports this is not an improvement over 1.12.0