use Memchmark qw(cmpthese);

...

cmpthese(BrowserUK => \&BrowserUK,
	 packed_default => \&packed_default,
	 SortKey => \&SortKey );
__end__

test: BrowserUK, memory used: 102006784 bytes
test: SortKey, memory used: 85598208 bytes
test: packed_default, memory used: 182788096 bytes