Yeah, AWS doesn't have the best speed to drive, though if you have money, you can specify how many IOPS you want... you just have to pay for your declared use every hour whether you're using it or not. It's also kinda hard to predict if you're not familiar with that kind of thing.

Note that on AWS your hard drive isn't on the machine running your VM. If you want to test local disk speed, do it in /mnt, where local disk storage is mounted... but remember that data stored there won't persist if you turn your instance off.