I have no idea if it is "right" since I'm not going to duplicate this exact benchmark, but it seems likely. Raw performance hasn't been a huge focus for Go, though this has been changing. The tip version produces much faster code than the last official release that seems to have been used here. Also you often get more efficient Go from the gccgo frontend than from the Google compiler since it can take advantage of a lot of front-end-neutral optimizations that gcc already has (though this gap is closing as the Google compiler gets improved). For the runtime, work continues on the goroutine scheduling, gc, etc.

Go is getting a lot faster and pretty quickly.