[jerf]

Heavy duty string bashing is a pessimal case for BEAM, yes. The two core data structures you could use for this, the binaries or the 'strings' (which are linked lists of characters), each have their own problems with this sort of algorithm. Erlang was designed to fling chunks around, maybe take a header apart before deciding where to fling a chunk around, not to grovel over every byte of some fairly-large string for detailed parsing.

Based on performance numbers I've seen, I'd expect a one-order-of-magnitude difference to be a more common case in general.