This page documents the time-complexity (aka "Big O" or "Big Oh") of various operations in current CPython. Other Python implementations (or older or still-under development versions of CPython) may have slightly different performance characteristics. However, it is generally safe to assume that they are not slower by more than a factor of O(log n). | wiki.python.org
I wrote Big-O: how code slows as data grows to explain Big-O notation. My goal was to explain it in broad strokes for people new to the idea.| nedbatchelder.com