No, map[string]int doesn't allocate ints. Why the map[string]*int version is faster is because it avoids a "write" to the map when you're not adding new words -

No, map[string]int doesn't allocate ints. Why the map[string]*int version is faster is because it avoids a "write" to the map when you're not adding new words -- it can just look up the pointer and increment what it points to. The Go compiler is not smart enough (yet) to optimize the former to avoid a map write. (That's my understanding, anyway.)