[genbattle]

Goroutines are multiplexed onto a set of threads defined by the Go program. They're not each a full thread; it's more like Stackless Python's version of threads. http://www.stackless.com/

[rocha]

Good point. Since the OP was talking about execution speed, I thought he was using the word thread to refer to OS threads.

[sausagefeet]

Even still, performing number crunching on 4000 Go thread seems like a bad idea.