Generics were a mistake. @ me in the parking lot about it.
which one?
We didn't pay for it, so I'm not going to drag anyone personally for something that's a cultural issue. If you're worried because you might use it, you'll see it in your benchmarks just like we did. If you don't have benchmarks, it's the least of your performance concerns.
In which case I'd recommend jerf's post at http://www.jerf.org/iri/post/2955, or my comments at https://news.ycombinator.com/item?id=30804253, or even just reasoning a bit from first principles about how intermediate slices would perform given Go's memory/execution model.