> R is somewhat slower Actually it's MUCH slower, up to a point of being entirely not usable for very large datasets (even ~100GB). True, much of MATLAB speed comes from using highly optimized BLAS (Math Kernel Library by Intel). But not just it. R lacks JIT optimization and numerous attempts to add it were unsuccessful. In fact it's so bad that Ross Ihaka, one of R's creator, proposed to "simply start over and build something better". See http://xianblog.wordpress.com/2010/09/13/simply-start-over-a...

TL;DR don't use R if you work with large datasets