Well the Infinity could punch a hole in the Forerunners best ship with MAC cannons (not sure how powerful these are), the super macs fire with 51.6 gigatons of TNT. The medium sized turbolasers of an Acclamator Troop Transport have a maximum output of 200 gigatons per shot, and were equipped with twelve of them. So I think it's safe to say the Star Wars has much more impressive ship weaponry and would easily defeat the forerunners. When it comes to the precursors it depends if neural physics can survive black holes.