Byrdie

Rendering with equivalent lights produces, on average, equal render times between Iray and 3Delight on CPU only renders. What you are looking at and comparing, though, is not equivalent lighting.Unfortunately Iray, for comparison purposes, does not have a disable Global Illumination setting. LOL. 

Want to get really silly? Load Uber Environment2 with an HDRI on it and with the 4x setting and with bounce turned on. Load Olympia HD, Lillith HD or similar. Render. 

Same lighting in Iray is accomplished by loading the HDRI in the Render Settings under Environment. Load Olympia HD Lillith HD, or similar, set the Render Sub-D to 3 under parameters and apply the Iray preset. Render. 

The two images, when the render is done, should be pretty close, the lighting is as close as 3Delight can get. What is the render time difference?