The lesson from both of these is that performance doesn't magically come from simplicity but it is enabled by simplicity. A complex system is always hard to opt

The lesson from both of these is that performance doesn't magically come from simplicity but it is enabled by simplicity. A complex system is always hard to optimise. A simple system may be easy to optimise. Building simple systems whilst keeping performance in mind is a delicate balancing act. Local optimisations tend to add complexity that may prevent later optimisations. Sweeping generalisations that reduce implementation complexity often inhibit later optimisation due to lack of information (eg http://lucumr.pocoo.org/2014/8/16/the-python-i-would-like-to-see/ http://lucumr.pocoo.org/2014/8/16/the-python-i-would-like-to...).