I emailed one of the developers about that. The A6 is very dynamic in how it adjusts its speed based on load to save power. I have run so many geekbench tests. On some low ends I have seen 800 on my iphone 5 and scores ranging all the way up to 1647. I think it is just the processor adjusting itself and GB might release an updated version of the app to give more accurate results.
So OP, I don't think your phone is faulty, it's just the nature of this new processor. Unless you are experiencing a lot of lag elsewhere in the OS.
Some of my scores (all 4 tests ran in a row with no apps open). Notice how the A6 increases speed each time to adjust for the conditions.