I found this on slashdot, and although he/she doesnt mention Perl, I found the question interesting and was hoping some clever feedback from this lovely community! Comments on slashdot is kinda cluttered and doesnt seem to discuss the topic much...
I have been thinking about this too lately. Specially the part where computers becomes faster and faster...
I usually say that if you wanna have low level access or really need to take the advantage of the CPU (do some advanced math computation is the usuall example), do in native language. Or well, do it in C/C++ or simular where you control every byte... But as computer becomes faster and faster one may wonder if this in the end matters that much.