Within the limitations of a scripting language, of course you try to get the best performance that you can.
However in general within a scripting language you are not trying to optimize things at the CPU cache level. You're worried about overall efficiency of your algorithms, avoiding disk, identifying performance bottlenecks, etc. But the pervasive use of hashes everywhere and memory hungry data structures makes careful use of CPU caches pretty much a lost cause.
Furthermore the language does so much behind your back that an analysis of performance from first principles is very unlikely to be right. Instead you need to benchmark.
However in general within a scripting language you are not trying to optimize things at the CPU cache level. You're worried about overall efficiency of your algorithms, avoiding disk, identifying performance bottlenecks, etc. But the pervasive use of hashes everywhere and memory hungry data structures makes careful use of CPU caches pretty much a lost cause.
Furthermore the language does so much behind your back that an analysis of performance from first principles is very unlikely to be right. Instead you need to benchmark.