Java is slow is a really old myth. It was once upon a time. Ofc there are caveats but looking at your average developer ... You will be fine. On the other hand

Java is slow is a really old myth. It was once upon a time. Ofc there are caveats but looking at your average developer ... You will be fine. On the other hand I would forbid an average developer the use of c/c++ and similar. It is just not worth it.