"But, if your experience is anything like my own, I'm guessing that a lot of what motivates you is the feeling that you've done something of tangible value when

"But, if your experience is anything like my own, I'm guessing that a lot of what motivates you is the feeling that you've done something of tangible value when you optimize the code." This is not at all how it is for me. The execution model of the code is core to how I read programs in languages where I am familiar with their execution model. So reading code that has dirty data or control flow, such as copying an entire array twice to change one character in two passes is as repulsive to me as maintaining and synchronizing two separate functions, one for each character swap.