Modern hardware is incredibly complex. It’s nearly impossible to reliably predict the performance outcome of the changes. Personally, when I work on optimizing

Modern hardware is incredibly complex. It’s nearly impossible to reliably predict the performance outcome of the changes. Personally, when I work on optimizing performance of my code, I throw away like 25% of my changes after profiling. Good architecture with well-defined levels of abstractions makes it easier to change algorithms, to replace implementation of algorithms with different ones, and so on. Even though abstractions are not always free performance-wise, often they do help fixing performance problems, albeit not directly.