strange go bench

gistfile1.txt

go test -v -bench=BenchmarkIteratorNext -benchmem
...
BenchmarkIteratorNext-8          2000732               576 ns/op               8 B/op          0 allocs/op



go test -v -bench=BenchmarkIteratorNext -benchmem -cpuprofile=cpu.out -memprofile=mem.out -memprofilerate=1
...
BenchmarkIteratorNext-8           513028              2746 ns/op               8 B/op          1 allocs/op



go test -v -bench=BenchmarkIteratorNext -benchmem -memprofile=mem.out -memprofilerate=1
...
BenchmarkIteratorNext-8           544665              2856 ns/op               7 B/op          0 allocs/op



go test -v -bench=BenchmarkIteratorNext -benchmem -memprofile=mem.out
...
BenchmarkIteratorNext-8          1892781               595 ns/op               8 B/op          0 allocs/op

go test -v -bench=BenchmarkIteratorNext -benchmem -cpuprofile=cpu.out
BenchmarkIteratorNext-8    1871590             611 ns/op               8 B/op          0 allocs/op


go test -v -bench=BenchmarkIteratorNext -benchmem -cpuprofile=cpu.out -memprofile=mem.out
BenchmarkIteratorNext-8          1892508               607 ns/op               8 B/op          0 allocs/op