Language implementations that share a compile target have the same lower bound for performance (being fast) but they have infinite and unrelated upper bounds for performance (being slow).
Let's say there's a Python to C compiler (there is) and let's say there's a C++ to C compiler (there was, may still be idk). The performance characteristics of programs compiled via both won't be very similar at all. They can't be any faster than C. They can both be much slower than it. They'll differ wildly from each other.
Let's say there's a Python to C compiler (there is) and let's say there's a C++ to C compiler (there was, may still be idk). The performance characteristics of programs compiled via both won't be very similar at all. They can't be any faster than C. They can both be much slower than it. They'll differ wildly from each other.