Rust hasn't really got 'faster' in that time, barring the odd optimizer improvement as noted in sibling. Much more likely that whatever benchmark you refer to has been rewritten for better performance.
Another major evolution is that SIMD is becoming part of stable Rust. It is available in C and C++ as GCC and Clang extensions, but not part of the standard language. Careful use of SIMD can result in fairly massive speedups across a wide range of problem domains.