The GC isn't very good yet, but brute-force sequential code can keep more state on the stack where it doesn't matter. (Just please codegen that instead of expecting everyone to read it.)
Go's GC is better than most of the Java GCs except the new ZGC and Azul's proprietary one. JIT makes some Java code faster. Ultimately, it's more about programmer expertise in a language rather than the actual language.
It's all relative. Go is optimized for pause times and beats all other mainstream runtimes for that. JVM GC is very configurable and can be optimized for throughput, pause times, heap size, fragmentation, or whatever you want, and can beat Go's for pretty much all of them except pause times. Both have very smart people working on them and the techniques are well established, so it's about tradeoffs. (An oldish post but I think still relevant: https://blog.plan99.net/modern-garbage-collection-911ef4f8bd...)
That said, Go's focus may be the right one for many use cases. On a high throughput service where you would assume you want to optimize for throughput, 100 ms pause times can wreak havoc because they're unpredictable and can cause work queues to explode and such. This isn't easily mitigated by load balancing. Whereas "less efficient" GC is at least predictable and you can just add a server to balance that extra work.
