From a technical perspective, Amazon has actually optimized this but turned that into "serverless functions": their ultra-optimized image paired with Firecracker achieve ultra-fast boot-up of virtual Linux machines. IIRC from when Firecracker was being introduced, they are booting up in sub-second times.
I wonder if Amazon would ever decide to offer booting the same image with the same hypervisor in EC2 as they do for lambdas?
I wonder if Amazon would ever decide to offer booting the same image with the same hypervisor in EC2 as they do for lambdas?