You will hear many times something along the lines of "Premature optimization is evil" in the responses to this, and I think they will probably be right. The kind of micro-optimizations you are looking at are really not going to make a blind bit of difference unless your program is already running very quickly - if it is running slowly then these are not the places you want to be looking for, you may want to profile your code using something like Devel::DProf to see where the time is really being spent. Of course if you are only just starting out to write the program then I would worry more about getting it working than performance at this stage.

If you are interested in the performance of individual Perl contructions then you can find this out yourself using the Benchmark module that comes with Perl.

/J\