Java is often slightly faster than Go, has similar (perhaps, older, better optimized Map) constructs, perhaps better GC (older, more optimized), though I don't think the GC is a challenge, has slower startup times - so I'd say roughly the same as the idiomatic Go version?
Java can be faster than Go, but it comes at the same cost as most "faster" things in software: Java uses significantly more memory.
Java is also more mature, which means you are entering a massive package-bloat setup that has evolved over the years to work for everyones wild and varied needs. By the time you have your database, cache, http/other handlers, tests, fixtures, metrics, logging, tracing, etc... setup you're looking at a scary pile of dependencies spanning thousands of classes that would make even NPM jealous.
Java’s GC is just incomparably better, literally every research on the topic is written for Java. Though that’s true that without value types, Java does rely slightly more on it.
