"Perl has very little to do with assembly language"

This is wrong as well.

*All* high-level languages are compiled into assembly/machine code to be understood by the processor(s).

"If you want it to run on just about any computer, then you should write it in Perl. If your goal is speed, then write it in assembly."

If you want to run something on any computer, use any language that can compile into machine code for the specific CPU architecture you're targeting.

If your goal is speed, write it in a compiled language (eg. C) instead of a scripting language.

If your goal is to write something that is so low-level that there isn't a compilation routine to do accurate translation, write it in assembly.