Erlang checks for overflow after arithmetic ops are performed internally (IIRC), so you are generally only penalized when overflow actually occurs and requires

Erlang checks for overflow after arithmetic ops are performed internally (IIRC), so you are generally only penalized when overflow actually occurs and requires promotion, which probably isn’t much different in performance from a language that would raise an error on overflow, though obviously not as efficient as a language that just wraps around on overflow.