Java is actually pretty fast, and certainly much, much faster than python. There are plenty of reasons Java isn't my preferred language, but speed is not one of them.
I think it's been out of date for a long time with modern computers having much more RAM and speedy SSDs (and also JVM optimizations). For actual run time performance once its loaded the JVM has had great performance in the early 00s already and improved since. And for server side it was never an issue as you don't restart the server very often (so the JVM is always already loaded).