The thing that's missing from this (and most) articles about the described kinds of code optimizations is context: when is it appropriate to make these kinds of optimizing changes, and when is it not?
> [with] this change ... the speed improved significantly [but] the readability and ease of coding decreased quite a bit
The speed of this specific function, measured with the described (micro) benchmark, improved, yes, no doubt. But that's not (by itself) relevant! If you want to use an optimized implementation of some code, it has to represent a significant improvement in the overall system as measured by meaningful, agreed-upon, high-level performance metrics.
If this function is called many times per user request, and the optimized version has a measurable impact on request latency, then sure, go for it! But, otherwise, making this kind of change is the textbook definition of premature optimization, never a good idea.
> [with] this change ... the speed improved significantly [but] the readability and ease of coding decreased quite a bit
The speed of this specific function, measured with the described (micro) benchmark, improved, yes, no doubt. But that's not (by itself) relevant! If you want to use an optimized implementation of some code, it has to represent a significant improvement in the overall system as measured by meaningful, agreed-upon, high-level performance metrics.
If this function is called many times per user request, and the optimized version has a measurable impact on request latency, then sure, go for it! But, otherwise, making this kind of change is the textbook definition of premature optimization, never a good idea.