250ms represents 96.15% of the total runtime. This is too short to meaningfully profile, the amount of time needs to be in seconds at least.
I strongly recommend you write your function as a testing.Benchmark the you get profiling for free and can adjust the amount of time each benchmark runs for.
http://dave.cheney.net/2013/06/30/how-to-write-benchmarks-in-go
http://go-talks.appspot.com/github.com/davecheney/presentations/writing-high-performance-go.slide#1