The patterns are not complex, but long, since they're made of all the elements of long arrays, separated by "|" (with the intent of alternatively match different patterns).

Then you'll likely benefit from running perl 5.10 or newer, since it implements a Trie optimization for alternations of literal patterns. If the arrays are really huge, you could increase the value of ${^RE_TRIE_MAXBUF} to make them all fit into the same trie.