Most people's slow Java applications are slow due to architecture/ecosystem, Java itself is pretty fast. That being said, I still prefer Go due to its elegant simplicity, easy concurrency, lack of runtime dependencies and better memory usage. Go's selective choice of which OO features to support also helps discourage some of the Java architectural bloat.
Not there are lots of reasons for choosing a platform, but if we are talking about performance:
A well written Go app tends to perform better as well: http://www.techempower.com/benchmarks/#section=data-r8&hw=i7...
Here it is with Java added back in too: http://www.techempower.com/benchmarks/#section=data-r8&hw=i7... . What is interesting here is any node entry only comes it at better than 10th place in one benchmark.
Most people's slow Java applications are slow due to architecture/ecosystem, Java itself is pretty fast. That being said, I still prefer Go due to its elegant simplicity, easy concurrency, lack of runtime dependencies and better memory usage. Go's selective choice of which OO features to support also helps discourage some of the Java architectural bloat.