Comment by twic

The JVM is excellent for throughput, once the program has warmed up, but it always has much more jitter than a more systemsy language like C++ or Rust. There are definitely use cases where you need to consistently react fast, where Java is not a good choice.

It also struggles with numeric work involving large matrices, because there isn't good support for that built into the language or standard library, and there isn't a well-developed library like NumPy to reach for.