We switched from Python to Julia for numeric code. It's generally much faster (and easier to optimize), and has slightly better syntax for mathy code.

It's worth noting that Julia is very similar to go, despite superficial differences. They're both small languages with big libraries, use the same concurrency model, use a mark-and-sweep GC with an emphasis on making it easy for the programmer to reduce garbage/allocations, and both use structs + functions rather than classes.