in reply to Ampersands and sub speed
Make sure you know what you are doing when adding & to the front of a function call. It can have unintended consequences if you do not understand the difference. Here is the relevant section from perlsub that briefly explains the difference:
To call subroutines: NAME(LIST); # & is optional with parentheses. NAME LIST; # Parentheses optional if predeclared/imported. &NAME(LIST); # Circumvent prototypes. &NAME; # Makes current @_ visible to called subroutine.