without an Nvidia video card on an dual Xeon Quad (8/16) 2.6GHz., 64GB RAM, Radeon HD 5770 with 1GB DDR5 (which Iray has no use for) it took 32 minutes to render a pair of glasses with two lights, so a plastic default shader used twice, once with a transparency at 1024x768 No other geometry in the scene. I was able to get better results out of LuxRender in 4 minutes.

If your using a decently powerful system without "a good nvidia card" expecting 10 minutes for a "reasonable" scene is not a realistic result. The engine was developed for Nvidia cards to take advantage of it, not CPU and RAM, they are an afterthought.

On the other hand the attached image took 5 minutes 43 seconds for 95% convergence, with a single 4ghz quad core i7. (Granted it took significantly less time with the Video cards turned on.) Image size is 1000x1300.

So whether you can get a decent image in 10 minutes or less depends on your lighting, your subject and your hardware, same as with any other render engine.