Currently the best performance with Raytraced and OpenCL happens on AMD cards with architecture GCN 2 or newer. For older cards there seems to be unfortunately a quite a big performance loss. You can check the list of AMD GPUs to see where your card stands.
I’ll be looking into how we can get Raytraced/Cycles to work on GCN 1 cards acceptably as well, but currently for such cards it is probably better to switch to CPU rendering for now
Clarification: AMD GPU of GCN 1 architecture will work, but performance isn’t what it could be.