If your using kerkythea, id suggest switchint to a biased render method, if i remeber correctly theyre a lot faster for doing interior scenes (which is a lot of the reason your lights take so long to render.)
In indigo there isnt really a lot you can do other than sit it out. Oh, and if your using the latest version of indigo you can put all the lights on seperate layers nd adjust how powerful tey are while the renders going. Useful stuff