A big part of Rust is that it lets you very easily parallelize things, even in super complicated situations, because it keeps it safe. The corresponding task mi

A big part of Rust is that it lets you very easily parallelize things, even in super complicated situations, because it keeps it safe. The corresponding task might certainly be possible in C++, but not necessarily always maintainable. Doing Servo's parallel styling or layout in C++ would be very hard. So it doesn't produce more efficient machine code, but it does open up new opportunities for optimization at a higher level.