Quarry's cause lag when they are breaking blocks because that normal causes lag on a a server. the only reason why water causes lag is because the server not only has to break a block but it then needs to have the water fill in one of thse blocks. that takes double the resources. Personally i think quarry holes are ugly, so when ever I see one I //regen the area or fill it in with dirt or stone. Chunks loaded don't really cause lag. that's a common myth some people believe and a myth the some server exploit by forcing you to donate to use them. I tell people to use a world anchor rather than AFK because it takes more server resources to have someone logged on loading 300+ chunks than it takes to keep 9 chunks loaded.