What exactly is a "virtual core" on Amazon EC2?
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The small Standard Instance is: 

> Small Instance (Default) 1.7 GB of memory, 1 EC2 Compute Unit (1 virtual core with 1 EC2 Compute Unit), 160 GB of local instance storage, 32-bit or 64-bit platform

Does this mean that you get access to an entire physical CPU core? Or are you sharing a more powerful core with other instances? 

Is your performance affected by other people sharing the same ***"physical core"*** or other hardware?
