An egress packet modifier includes a script parser and a pipeline of processing stages. Rather than performing egress modifications using a processor that fetches and decodes and executes instructions in a classic processor fashion, and rather than storing a packet in memory and reading it out and modifying it and writing it back, the packet modifier pipeline processes the packet by passing parts of the packet through the pipeline. A processor identifies particular egress modifications to be performed by placing a script code at the beginning of the packet. The script parser then uses the code to identify a specific script of opcodes, where each opcode defines a modification. As a part passes through a stage, the stage can carry out the modification of such an opcode. As realized using current semiconductor fabrication process, the packet modifier can modify 200M packets/second at a sustained rate of up to 100 gigabits/second.