Hubs are nodes which have numerous links. Optimally, the speedup from parallelization would be linear-doubling the number of processing elements ought to halve the runtime, and doubling it a second time ought to again halve the runtime. Mainstream parallel programming languages stay either explicitly parallel or (at best) partially implicit, in which a programmer offers the compiler directives for parallelization. However, a number of new programming languages and platforms have been built to do common purpose computation on GPUs with both Nvidia and AMD releasing programming environments with CUDA and Stream SDK respectively.