Warm pools are a supported feature in AWS on auto scaling groups. Works as you're describing (have a pool of instances in stopped state ready to use, only pay f

Warm pools are a supported feature in AWS on auto scaling groups. Works as you're describing (have a pool of instances in stopped state ready to use, only pay for EBS volume if relevant) https://aws.amazon.com/blogs/compute/scaling-your-applications-faster-with-ec2-auto-scaling-warm-pools/ https://aws.amazon.com/blogs/compute/scaling-your-applicatio...