I've been working on building and testing a private ethereum network using geth and commodity AWS hardware. I'm curious if it's realistic to expect 14s block times in this case? What I see is very fast block times at the beginning of a new chain, but then it slows to around 21s block times within the first 20,000 blocks.
This turned out to be a resource problem. Once I allowed geth to use multiple minerthreads, the block times hit a more typical average of around 14-15 seconds.