If "k4a" is the Kindle for Adroid app, then Yes. I do use it. I don't find it at all sluggish (this is on a Nexus 7). But I don't particularly like the navigation. The Back button doesn't always work properly, and it's easy to lose your place.
Have you tried any other reading apps on your S3? How does the Kindle app compare with them, sluggishness-wise?
Mike
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