Presumably that instead of writing a language that targets a slow language and pays a multiplicative slowdown on top of that, you could write something that targets a relatively fast language that Python is able to run in also, and pay the multiplicative price against that instead. Go is not the fastest language and I expect it to have roughly a 2x slowdown over C indefinitely, but that still puts it in the "compiled language" camp rather than the "interpreted language" camp, which tends to run 10x-40x slowdown.