Thank you Hans for searching how to accelerate a Java program, but pointing to an article which is 13 years old (an eternity in computer programming) couldn't lead anywhere. Java has made leaps in performance since that time.
Anne, you should check first that when a photo is rendered at one of the two best quality levels, there appears 6 colored squares during the rendering process since your processor has six cores. Then, you should try to increase the max memory used by Sweet Home 3D to 1 or 2 GB; this should really help. Finally, you could try the Java 7 as soon as a beta version will be available (this should happen in February).
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Emmanuel Puybaret, Sweet Home 3D creator
