I have been using Octave and MATLAB for a few projects, and I\'ve come across a few questions. This question Why/when should I prefer MATLAB over Octave?) answered several,
There are four ways how Matlab code gets sped up:
JIT: compiling at runtime helps with loops but seems to speed up (or at least interact with) other parts of the code as well, according to my anecdotal observations.
Implementing functions in C/C++: There's a bunch of Matlab/Octave functions that are implemented in Matlab/Octave. At every release, there's a bunch more of them that get made into built-ins.
Multithreading: There's a list of functions that have multithreaded implementations, which will speed up function calls.
Generally more efficient implementations. For example the median filter got a massive speed boost for integer inputs a few releases ago.
All of these approaches need developers dedicated to make code faster. As far as I know, a major concern of Octave developers is to make sure (Matlab) functionality is there at all, whereas performance increase seems to have been a focus of Matlab development in the last few years.