I mean, yes, if slow function calls are a problem then yes it is a language issue that really long term aught to be handled by fixing the implementation. But on the other hand we are engineers and problem solvers that have to work with the tools we have.
Sure. But if Perl's function calls are "too slow", where does that leave you with Perl? You can't do functional-style programming, because that would use too many function calls. And you can't do object-oriented style programming, because that would also use too many function calls, and method calls are slower than regular function calls. And you can't write any big or complex programs, because big complex programs are full of functions and then they must be too slow.
So where does that leave you? I think it leaves you with "Perl is just a scripting language, only good for throwaway scripts, but nothing big or important." Which some people do believe, but I do not.
Basically, my argument is this: Some language features can be avoided, but functions are not one of those features. Some implementation deficiencies can be worked around, but if function calls are too slow, there is no workaround. Every nontrivial program must contain lots of function calls. So if Perl's function calls are "too slow" (whatever that means, and nobody in this thread has suggested any relevant meaning) then you have only two choices. One is to fix Perl. The other, as you said, is to be a problem-solving engineer, to recognize that you are in a hopeless situation, and to obtain a tool that is not hopelessly defective. I have recently been informed that Java's function calls are faster than Perl's; perhaps that would be a better choice.
But it seems to me that you cannot reasonably hold the opinion that Perl is worth using for nontrivial programs and also that Perl's function calls are too slow to use.
I found your description of "constructing tailored code..." etc. above really interesting, but I can't imagine what it looks like, or what you could be doing that the function-call overhead is the bottleneck. I can only imagine that what you are doing does not really make sense, or that it is such a weird special situation that it has little applicability to general discussions like this one. I suppose this is just a failure of my imagination, but I certainly would like to see it.
Anyway, I was hoping that HOP had stuff along this line...
Wouldn't it better if it had something in it that you hadn't already thought of?