Things to know about performance of code:
- You need to know how many cores you really have. If you have a machine with "hyper-threading", you can have two actual cores, but they appear to the OS as four. Therefore, it's possible to have something like a Core2Duo in your laptop and a 2-core processor in your desktop, and have the same number of cores. Look up the spec sheet for your processor to find out.
- Parallel execution can be implicit or explicit. Some MATLAB functions are multithreaded, and will automatically take advantage. Others are not. Other functions (in combination with the Parallel Computing Toolbox) will take advantage of multiple cores, but you must change your code to use parallel computing constructs (parfor, spmd, etc)
- The most valuable thing you can do to search for speedup is to use the profiler to see what's taking up the most time in your code. Otherwise it's just guesswork and pre-optimization. It's possible that you are waiting on something like disk I/O to read a file and parse it, or there is some other bit of code that's written inefficiently, or you aren't preallocating, you could vectorize, etc.
