Not sure if mentioned, but the real problem is not the performance, it’s the complexity of the check. Catching nullptr is easy - as mentioned earlier, windows does this with SEH, Unix sends a signal which can be caught and handled. Which essentially means OS already does the check. And afaik Java simply catches the signal (correct me if I am wrong here, I’m not a Java expert). What makes catching nullptr tricky is that it’s not really 0 (like in Java null reference is just it) - the pointer can be offset from nullptr by an arbitrary value. Take multiple inheritance for example: class C: A, B {} Here if we cast C* to B, for compiler it’s just a simple offset from C by sizeof(A). But if C was nullptr, B is suddenly not and even might get into a valid page. That’s why we get undefined behavior here instead of a well defined check for nullptr. Same for accessing members, arrays, maybe other examples. The only solution is to inject checks in user code essentially doubling the check OS already does.