More generally than the other replies, BQN is an array language, and as such "a+b" & "a×b" etc automatically map over arrays, and the interpreter can thus trivi

More generally than the other replies, BQN is an array language, and as such "a+b" & "a×b" etc automatically map over arrays, and the interpreter can thus trivially vectorize them (and, if you're curious, yes, in a naive interpreter (which CBQN currently is) this does mean intermediate arrays go through memory, which is probably a significant part of the difference in speed).