I wasn't finished with my reply, but I had to walk the dogs.

Some other things you can do to speed up Ray-tracing are: keep the amounts of lights that have  Ray-tracing enabled as low as possible, just one infinite light is enough to similate sunshine, but produces very hard shadows.
If you have complex objects in your scene that aren't reflective (like hair) you can uncheck the "visible in ray-tracing" option in the properties(unless you want a shadow of it, but it will increase your rendertime)
Minimize the amount of reflective or transparant objects in your scene.
On the other hand: if you want an interesting picture with shiny, reflective and transparant features ray-tracing is in my opinion the best you can have, and you have to take the extra rendertime for granted.

-How can you improve things when you don't make mistakes?