Julia has a lot of room for improvements. For example with better type inference (programs get slooow when the type cannot be inferred, they are working on it) and stack-allocation of arrays.

Currently, all arrays require a malloc. Once the JIT-compiler is sufficiently smart, Julia could use stack-allocation of temporary arrays (that cannot escape the current context). Algorithms making use of temporary arrays will become faster by possibly an order of magnitude.

Julia might become competitive with C / Fortran for general purpose computing. And that is a level of speed all your other examples cannot hope to reach.