benchmark                                old ns/op    new ns/op    delta
BenchmarkCompareStringEqual                     51           35  -30.20%
BenchmarkCompareStringIdentical                 51            7  -85.71%
BenchmarkCompareStringSameLength                25           18  -28.29%
BenchmarkCompareStringDifferentLength            2            2   +1.46%

R=golang-dev, rsc
CC=golang-dev, remy
https://golang.org/cl/6450092