I like to build large gold farms on servers, but the entity count can be a problem - causing unnecesary lag when any player is near it.

So this is very simple to use way of switching the gold farm on and off, by using dispensers with flint and steel and dispanser with water.

It can be wired in to a preassure plate at the entrance to the gold farm to make it super easy. (as the same button activates and deactivates it)