How Could a Letter Influence Your Code’s Performance?

Developer: I’m going to write a new software application. It will be the fastest ever!
Manager: How fast?
Developer: So fast that it will make your head spin!
Manager: Why would anyone want their head to spin?

In the early days of computing, there was only one way to judge a computer’s performance: how fast it could calculate. 

But as time passed, we started writing sloppy software that managed to bring even the most powerful computers to their knees. This situation can be avoided by teaching new developers the importance of clean and performant code from the start. 
And it all starts with understanding Big O notation and how to use it.