Which features in particular?

One of C++'s core tenants is (and has been since the 90's) zero-cost abstractions. Or really, "zero-runtime-cost abstractions"; compile times tend to increase.

Obviously some abstractions necessarily require more computation (e.g. raw pointers vs reference-counted smart pointers). But in many cases new features (if implemented correctly!) give better semantics and additional compile-time safety while still compiling down to equivalent binary.