First thing you should look at on the Rpi is having a good power supply. Cheap old cellphone chargers won't cut it. I've had good success with the Canakit adapter. Since your program is I/O limited, finding a quality SD card is the second thing you should look at. Afraid I'm not as much help for this, but I usually buy Class 10 cards and get along OK.

Looking at your list of modules, you should get rid of threads and threads::shared, preferably rewriting those pieces with fork(), or perhaps AnyEvent. A threaded perl build is noticeably slower than a non-threaded perl, and exists mainly to do pretend fork()s on Windows.

(As an aside, I just noticed that the default Raspbian perl5.14.2 is compiled with threads. I'm not sure, but hiveberry may come with a perl without threads.)

You can also ditch Switch and rewrite those parts as an if/elsif series, or perhaps given/when if you're feeling adventurous:

http://perldoc.perl.org/perlsyn.html#Switch-Statements

Just doing those, I think you'll be able to chew off a few seconds at startup time.