The most important characteristic of a micro instance is not the raw performance per se but how the workload is distributed. It's not suitable for a task where a a steady performance is required, micro instance designed for short but intensive burst. AWS monitors micro instances and degred performance when needed to allow other instances to run. Right now there are not that many micro instances are in use, probably they are not as strict but this will change at the future for sure. For more info check they documentation: http://docs.amazonwebservices.com/AWSEC2/latest/DeveloperGui...