A method for performing a lookup for a packet in a computer network are disclosed. The packet includes a header. The method includes providing a parser, providing a lookup engine coupled with the parser, and providing a processor coupled with the lookup engine. The parser is for parsing the packet for the header prior to receipt of the packet being completed. The lookup engine performs a lookup for the header and returns a resultant. In one aspect, the lookup includes performing a local lookup of a cache that includes resultants of previous lookups. The processor processes the resultant.