In my case, if I turn the bloom back on, it reverts all of my shaders to high, which in turn gives me 5 fps. Any other setting, and the blob stays bright white. I honestly believe this is a coding error, because pre 1.3, the light above my head simply didn't emit a light at all - just a bouncy probe. And that made sense to me, mostly because with the shaders on very low, all rooms look brightly lit.