take a look at the Eff(iciency) parameter at the statistics. It should be >100% otherwise your lighting levels are too low.

Luxrender shoud be taken as a camera: when the ISO is low and/or the fStop is small (= high value) and/or there is little light in the scene, it takes a long time to get the film sufficiently exposed = to grain out of the render.

Use the lighting tab to raise light levels and/or auto-settings to get an idea of the ISO/fStop settings for your lighting.

Just to benchmark, what are your statistics on the watch (luxtime) scene that comes with the LuxRender package (or can be downloaded from there). On my machine: 1166% Eff, producing 84 kSamples/second (= 84.000/(800x600) =0.175 samples/pixel per second on a 800x600 image) so it will take 500/0.175 = 2850 sec = 47,5 minutes to reach the 500 samples/pixel quality requirement. I'm running 6 cores = 12 threads @ 4GHz.

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Usually I'm wrong. But to be effective and efficient, I don't need to be correct or accurate.

visit www.aRtBeeWeb.nl (works) or Missing Manuals (tutorials & reviews) - both need an update though