Feeding data to 1000 CPUs – comparison of S3, Google, Azure storage
AWS has a limit on the total throughput any one <i>account</i> can have to S3, so the more CPUs OP adds, the worse OPs performance will be on each one.  I suspect the other providers have the same restriction.<p>I either missed it or OP didn't specify how many instances they was using at once to run their benchmark, but the more instances they used, the worse it will be per node.<p>This did not seem to be accounted for.<p>EDIT:  OP says below it was from one instance, so what I said doesn't apply to this writeup.