I've not seen anything like the dynamic-dispatch optimisations the Self team came up with in the 1990s done in C++, nor problem-domain optimisations expressed as macros as is often done in Lisps, nor the aggressive constant-propagation of closures and their eventual inlining that Factor does.

Perhaps some of them could be applied, but a highly complicated base language with extensive mutation semantics (including pointer aliasing) probably mean they'll be so limited in their applicable scope, and so difficult to implement, that it's not an attractive activity for C++ compiler writers...