I haven't found any choppiness when playing Angry Birds on the Vox, and I use the Getjar apps as well.
I noticed the other day that the keyboard was more sluggish than usual. When I checked available RAM (under Manage Apps/Running) I found the ratio of RAM used to free RAM was high. Rebooting the Vox freed up the RAM and using the keyboard was back to it's normal speed.
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