It actually really runs slower as is it first an interpreter, and the compiler is yet to be optimized to GCC levels; but is has a great compiler infrastructure that could eventually JIT to faster code (it being a runtime compilation, that has statistics, and Graal being capable of partial evaluation)
I was merely pointing at a hole in your argument: the language of the compiler has absolutely no influence in the quality of it's output (again: the JVM compiles to assembly, not to C++).
A compiler written in brainfuck could write code that is more performant than gcc does.
The language does have an influence on compilation speed, though. But that matter in your argument?
That's not the statement you made. A safer statement would be, "a simple interpreter for language x, implemented in language y, cannot be faster than language y".
My statement is that language speed comparisons are stupid, but if you're willing to make one, you cannot beat the language you're written in. That's like saying Shakespeare writes better stories than...English.
Whereas Java written in C could run Java code.