>> I'm willing to bet that 99% of the performance difference will be solved by value types. Anyway, Cliff Click, who wrote H2O[1], a large machine learning plat

>> I'm willing to bet that 99% of the performance difference will be solved by value types. Anyway, Cliff Click, who wrote H2O[1], a large machine learning platform, reports achieving Fortran speeds (i.e. maximum throughput) with pure Java[2]. This means that a C application won't even be 1% faster. I've had a personal conversation with Cliff himself. Java no matter what you do can't deal with hardware acceleration and gpus. We agreed on that. Numerical software is a different beast. I also kept mentioning "simd instructions" as well as things like openmp. You are talking about systems software. Unfortunately that matters a lot for machine learning. The axis along which you can get equivalent speeds should be specified here. "values types" != "runs on faster chips" You aren't likely to beat intel or nvidia's compilers at their own game here . Java will always be playing catch up to last gen's tech there. Disclosure: I'm more than aware of what's going on in the space. We compete with them for customers and have a very clear understanding of their offerings. H20 has a great k/v store based on the exact mechanics you're talking about. That's about it though. Also of note: Cliff doesn't work on h20 anymore: https://twitter.com/cliff_click/status/700817408110399492 https://twitter.com/cliff_click/status/700817408110399492 >> Oh, sure, for some specialized use cases of course that's true, but you could use OpenCL in Java, too.... OpenCL isn't exactly the industry standard for this stuff. You always end up using cuda, and you always end up dropping down to c. There's just no way to avoid that if you want the fastest out there. Another disclosure, we work closely with nvidia and I may be biased: https://blogs.nvidia.com/blog/2016/10/06/how-skymind-nvidia-deep-learning/ https://blogs.nvidia.com/blog/2016/10/06/how-skymind-nvidia-... I agree with you on the last part, but I keep mentioning "numerical software" for a reason. There are certain things the JVM is good at, writing a database and systems software is one of those things. There are still bits of HDFS in c++ though. I don't think you'll be able to get around having bits of your code in c which is what I emphasize here.