Stop comparing Amazon with your DC
Amazon SLA defines each of their instances in ECUs. Sometime ago it was equivalent to a 2Ghz Athlon core.
Any performance variance is more than what one has paid for.
And, no: the processor has nothing to do with the speed of an instance. You got hosted in the same rack of some fanatic about big-data and you are toasted. Regardless of the cool new CPU you might have obtained.
So, the "study" can only affirm that Amazon uses different processors and that it maintains its machines somewhat updated. Whenever performance is a concern Amazon sells Reserved Instances but, not surprisingly, the price is on the high side.
Stop at comparing Amazon with an on-premise infrastructure. The Cloud is a model that allows fast deployment and better scalability (then add your business reason here).
- It doesn't cost less
- It doesn't do everything
- It will never solve the issue of data confidentiality but, eventually, it will make us get used not to worry about it.