In an interview, I was asked to analyse the complexity (and thus relative performance) of a piece of C code extracted from functioning production software. As a follow up, I will demonstrate the process of identifying a performance problem and implementing a solution to it. The code had originally been given as part of a pre-interview exam, where general issues with the code were to be discussed. I won’t be posting solutions to the pre-interview exam question (there will be potential problems with the code) and I have changed the structure of the code so it’s not searchable for future candidates.