Yeah I figured as much. :)
But as a personal habit i prefer to leave such work to the compiler. Because otherwise it makes the code less readable and compilers these days are pretty good at figuring how to optimize it.
Just now I tested following 'snippet'
```go
	// var z int
	for i := 0; i < 10000000000; i++ {
                // z = i + 1
		z := i + 1
		noop2(z)
	}
```
and z:= i seems to be faster by 6 ms ;) which implies no additional overhead of stack allocation

Anyway after looking again at the timer calc code I see that it still could use some improvement in terms of readability and variable/code reuse.
I plan to rewrite it a little in next PR to support multiple Percentile thresholds just like latest etsy/statsd. 
But if you prefer to move the variable declarations out of the loop I can amend this PR.