"But, in my opinion, it's not that bad."

Firefly is way, way too slow compared to what even my lowly I5 laptop with its NVIDIA GeForce is capeable of.

I'm not too unhappy with the current quality, but hour long renders just for a few figures and props in 2013 ?

Yes, most renders I do are finished under five minutes, but I use a lot of tricks and make compromises in quality, but Firefly is very easy to overload even in simple scenes.

Try render a meadow with actual grass and weeds and it'll easily slow down to a crawl with even a single figure.