I'm testing caustics on a quite large scene with a lot of glass and reflective materials. In this scene there are 3 houses and a lot of scattered vegetation.
The first test was not good. I turned off the grass scatter to try to improve the speed.
Second test with a simplified scene, just one house, some trees and the ground was on.
With this scene it started to work quite well.
The main problem that I see is that with large scenes with a lot of metallic or glass materials, the computation can be quite slow. If we can have a button to deactivate reflective caustics from materials that are not important, maybe we can have faster caustics.
The rayswitch option is not the best one, especially when working with a lot of different shaders.