I'd say it's efficient the way BlackBerryOS is efficient - they're OSs optimized to run on mobile hardware, largely from the earlier days. They're so melded optimization-wise to their hardware, that for their functionality, they don't need that many resources. However, that doesn't mean that simply giving them more resources would scale their functionality, if their optimizations are such that cause performance to simply cap out before the hardware specs do. That said, I'd guess that something like web page rendering and the like would happen faster.