Hi Maga, got some similar observations. Bryce obviously "froze", when reaching specific parts of my scenes, that suddenly involved additional transparent material, reflections or light-sources!! Just wait, as RKane_1 suggested, for 20..30 minutes, if it slightly crawls to the next percent-value or screen-line. Where does it stop? Same screen-line? Reaching specific objects/materials?!! Or take one of the lenses out as a test-file, if this speeds up the calculation. I assume, its rather due to some objects, that suddenly get involved and which need a considerable amount of calculation-power. Cheers, Hubert

"All that we see or fear, is but a Sphere inside a Sphere."     (E. A. Pryce -- Tuesday afternoon, 1845)