At least for me, Julia&#x27;s fast enough in most cases.  I switched from C&#x2F;C++ to Julia for all of my scientific work, and it runs fine, even on a supercomputer like Titan (barring something that requires thousands of nodes at once — MPI is not yet integrated into Julia).  You just have to be careful in the tight inner loops and check the assembly that it outputs using code_native().<p>Granted, there&#x27;s plenty of fast libraries written in C&#x2F;Fortran that don&#x27;t have a Julia equivalent yet, and depending on the overhead of ccall(), you may wish to stick with writing the rest of your code in the language of the library.