So ... what?
I have no idea what spiders are, and I've no idea what you're saying here. Are you trying to defend a 4k line class?
There are several areas that requires a nasty large code, and complex one on top of that. These are some algorithms from image processing, handling interactions between 1 mill+ entities, handling and analysis of a geographic data, and sometimes also the smart AI.
I seen a 1000 line implementation of DCT. (My implementation of DCT isn't as large, but it needs 2000 operations per load.) There are much more code intensive algorithms however.
Spiders is name for... Let's suppose you'd have these data: "1324", and you need to convert that into this "1234". You'd select one of methods that is called spider.