Please answer these questions before submitting your issue. Thanks!

1. What version of Go are you using (go version)?

go version devel +bd72497 Mon Apr 11 01:52:10 2016 +0000 darwin/amd64

1. What operating system and processor architecture are you using (go env)?

darwin/amd64

1. What did you do?
   Run this program

package main

import (
        "fmt"
        "time"
)

func main() {
        t1 := time.Now().Add(-1 * time.Second) // ensure there is no collision on first iteration
        for {
                t2 := time.Now()
                d := t2.Sub(t1)
                if d == 0 {
                        fmt.Println("collision at", t2)
                }
                t1 = t2
        }
}

1. What did you expect to see?

This program should cause 100% cpu usage.

1. What did you see instead?

The program causes 100% cpu usage, but taskgated is also heavily used , around 20% on my system.

https://developer.apple.com/library/mac/documentation/Darwin/Reference/ManPages/man8/taskgated.8.html

Reports that taskgated is responsible for implemting the mach task_for_pid syscall (?), so it looks like we're calling this syscall many times, we should probably not do that and cache the task port once per process.