For a long time, I've been of the opinion that after a certain point, optimisation becomes counter-productive. It happens on two fronts. One, you are spending exponential time for linear (if you're lucky) gains in performance. On the other hand, you are making your system overly sensetive to perturbations in the initial assumptions. And all for what? So your system will run in 5 seconds instead of 10. For me, I'll take the less optomized, more stable solution every time. It makes my life easier, but more importantly, makes others' lives easier when they have to maintain anything that I've written.