While in general I indeed think that people should profile code before they optimize it, I also think that they should avoid unnecessarily pessimising it by wri

While in general I indeed think that people should profile code before they optimize it, I also think that they should avoid unnecessarily pessimising it by writing code that is not exactly idiomatic and is known to have an overhead. In this particular case I am not sure I would prefer slicing+forEach to writing a old-style for-loop on any relatively hot path. Of course either profiling or thorough knowledge of the code should be applied before making this decision to determine whether this code path is hot or not, what's the average size of the array and so on. The main motivation for this decision would be the fact that slice produces the copy of the array. This is both hindrance in terms of performance (as VMs right now would not elide copy operation) and in terms of readability (e.g. when I see such code I would have to ask myself: does doOtherFunction require fresh copy or not, does it use only the first argument or all of what forEach passes into it and so on?). So you can see the choice for me is pretty complicated.