t3 instances on AWS have burst capacity charges if you choose unlimited. It's $0.05 per vCPU-hour, and is only charged if you exceed the accumulated burst capac

t3 instances on AWS have burst capacity charges if you choose unlimited. It's $0.05 per vCPU-hour, and is only charged if you exceed the accumulated burst capacity. So running a t3 would allow you to pay for a baseline and then only pay for the CPU you end up needing beyond that baseline.