Best approaches to performance analysis

Good coding practices and project asset management often make finding the root cause of a performance issue relatively simple, at which point the only real problem is figuring out how to improve the code. For instance, if the method only processes a single gigantic for loop, then it will be a pretty safe assumption that the problem is either with how many iterations the loop is performing, whether or not the loop is causing cache misses by reading memory in a non-sequential fashion, how much work is done in each iteration, or how much work it takes to prepare for the next iteration.

Of course, whether we're working individually or in a group setting, a lot of our code is not always written in the cleanest way possible, and we should expect to have to profile some poor coding work from time to time. Sometimes, we are forced to implement...