Everything in second life is sent to the client (which usually tries to cache). Eg you can even build new geometries ingame. Viewers are "game clients" yes. Th

Everything in second life is sent to the client (which usually tries to cache). Eg you can even build new geometries ingame. Viewers are "game clients" yes. The viewer is intended to mostly be a dumb receiver. The server does most lifting. Firestorm is a fork of the official viewer. It forked about the time I played SL but seems to have grown into it's own these days.