Summary
When it comes to performance, there is no holy grail, no single thing you can do to ensure peak performance in all cases. This shouldn't worry you however, as in most cases you will never need to tune the performance and if you do, a single tweak could probably fix your problem. You should be able to find performance problems and memory leaks in your code now which is what matters most, so just try to contain yourself and only tweak when it's actually needed.
The most important outtakes from this chapter are:
Test before you invest any effort. Making some functions faster seems like a great achievement but it is only rarely needed.
Choosing the correct data structure/algorithm is much more effective than any other performance optimization.
Circular references drain the memory until the garbage collector starts cleaning.
Slots are not worth the effort.
The next chapter will discuss multiprocessing, a library which makes it trivial to employ multiple processors for your scripts. If you can...
