C/C++ isn’t really faster than Rust. That’s the attraction of Rust; safety AND speed.

Of course it also depends on the job.

https://benchmarksgame-team.pages.debian.net/benchmarksgame/box-plot-summary-charts.html

Rust is faster than C. Iterators and mutable noalias can be optimized better. There’s still FORTRAN code in use because it’s noalias and therefore faster

But yeah I dunno in what cases rust is faster than C/C++.

First of all C and C++ are very different, C is faster than C++. Rust is not intrinsically faster than C in the same way that C is faster than C++, however there’s a huge difference, safety.

Imagine the following C function:

void do_something(Person* person);

Are you sure that you can pass NULL? Or that it won’t delete your object? Or delete later? Or anything, you need to know what the function does to be sure and/or perform lots of tests, e.g. the proper use of that function might be something like:

if( person ) {
  person_uses++;
  do_something(person);
}

...

if( --person_uses == 0 )
  free( person )

That’s a lot more calls than just calling the function, but it’s also a lot more secure.

In C++ this is somewhat solved by using smart pointers, e.g.

void do_something(std::unique_ptr person);
void something_else(std::shared_ptr person);

That’s a lot more secure and readable, but also a lot slower. Rust achieves the C++ level of security and readability using only the equivalent of a single C call by performing pre-compile analysis and making the assembly both fast and secure.

Can the same thing be done on C? Absolutely, you could use macros instead of ifs and counters and have a very fast and safe code but not easy to read at all. The thing is Rust makes it easy to write fast and safe code, C is faster but safe C is slower, and since you always want safe code Rust ends up being faster for most applications.