"The EC2 ephemeral disks normally clock in at 6-7ms latency, that's >13x slower than dedicated disks." Um. Are you comparing hard drives to SSDs? Rotational

"The EC2 ephemeral disks normally clock in at 6-7ms latency, that's >13x slower than dedicated disks." Um. Are you comparing hard drives to SSDs? Rotational latency for a 15k drive is a couple of milliseconds. Seek time for server drives varies from 3-10ms. EC2 disks are slow, but there's no way they're 13 fold slower than your average server drives. And 6-7ms is just about on par with commodity hardware.