Its hard to say what performance you can expect as it depends on the amount of pixels x lights that need to be calculated. A GT550M (guessing its an M series as its a laptop) Is a pretty low end GPU that's now 7 years old. I really don't think it would be be able to handle this effect even on the lowest settings. You could try setting the sample count to something extremely low and set the resolution to half (quarter is only faster if you're rendering a lot of lights). also turn off some of the advanced effects like density particles. But even then i think that GPU would only be able to handle 1 low quality realtime volumetric light.