[btilly]

That is a worthwhile option, but parallelization hasn't generally offered me nearly that much of a win when I'm limited by memory access performance.

In my experience, you're best off optimizing relatively limited pieces of a system rather than big applications. And only consider the rewrite when you've looked at optimizing it in place. This means that the thing that needs to be optimized with a rewrite often has a chance of not having any giant stupid mistakes.

For example see http://bentilly.blogspot.com/2011/02/finding-related-items.h... for a case where I found a thousandfold speed increase by rewriting from SQL to C++. As much as was reasonably possible, I did not change the basic algorithm.