The inefficiency is about going through kernel that will then dispatch some signal and the signal handler has to analyze what exactly happened, that is not a sl

The inefficiency is about going through kernel that will then dispatch some signal and the signal handler has to analyze what exactly happened, that is not a slow path, but ridiculously slow path. OTOH, my view is somewhat LISP-centric and just implementing + by passing the arguments to taddcctv would be problematic, in the Smalltalk world, implementing SmallInteger>>#+ like that makes sense.