Managed to reproduce the issue on another S3 and fix it. Try adding this CSS rule to your page (remove the previous ones):
.km-ios /* use .km-android, when you're not forcing the iOS styling) */
-webkit-transition: -webkit-transform .0001ms;
The problem was that simple 3D translation is not enough to switch on 3D acceleration in the S3's native browser (and probably PhoneGap, since it uses the same engine). To switch on 3D acceleration, a transition is now needed, no matter how short. I'm not sure what will be the effect of this rule in the iOS browser, so be sure to include it only in your Android version.
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