sumatra is for parallelizing mainly on GPU, not for SIMD - current C/C++ compilers neither do that. Java has SIMD support for quite a long while now, probably since Java 6 or even earlier and generally C-like Java code using raw arrays and primitives is as-fast-as-C these days. I'd be more afraid of lack of true value types in Java. This one thing makes C still a better choice for high performance stuff.