It depends on how you look at it. One could argue "nothing". Remove anything, and it's no longer Perl. On the other hand, one could say "almost everything". Remove everything from Perl till all you have left is C, and you can do anything with it that you can with Perl. And you don't even need to stop there - there are a lot of things that can be removed from C as well. For instance, you can get rid of all the libraries, including 'libc'.

Of course, what you really want is something only you can answer. After all, you write:

I'm looking for other ways to shave down the size, remove the parts that aren't needed, and still retain the functionality that I require.

What the functionality is that you require is only you can answer. And what's needed? OO isn't needed, regexes aren't needed, hashes aren't needed, dynamic loading of libraries aren't needed, XS isn't needed, looping constructs aren't needed, references aren't needed, strings aren't needed, in fact, very little is "needed".

But would it be Perl?

Abigail