> However, this kind of “performance tuning” is not necessarily portable, not between different compilers, nor between different hardware architectures on the s

> However, this kind of “performance tuning” is not necessarily portable, not between different compilers, nor between different hardware architectures on the same compiler, nor between different versions of the same compiler. I do recall a time when we unrolled loops to minimize the number of decrement+jump instructions. Then there was a time when we stopped doing such in order to minimize the code size and increase the likelihood of it fitting into the cache. Later on loop unrolling became a thing again in order not to upset the CPU's branch predictor ... So yes, definitively depending on architecture and pointless w/o testing.