A trading system doesn't have a single hot spot that can be easily optimized. The critic paths can be hundreds of thousands of line of code. There a lot of sep

A trading system doesn't have a single hot spot that can be easily optimized. The critic paths can be hundreds of thousands of line of code. There a lot of separate processes and subsystem that do not need to be absolutely latency optimal (or even at all), that are definitely amenable to be written on other languages. Of course when you already have a bunch of C++ programmes, things tend to end up being written in C++ even if it is not strictly necessary.