I had this problem trying to make a torch look right and had to settle for a whole family of over-lapping spots... worked out for the best when it came to animating the flickering light. Kill the shadows on any you can to speed rendering. I didn't know pulling a omni light was a possibilty? I've been under the impression that they were fixed to a virtual spere outside the studio... like being able to move the sun and moon around, but not being able to take them out of the sky. I gotta look into that.