This is still a thing, Fargate pull times are super slow: https://github.com/aws/containers-roadmap/issues/696. We run all of our workloads on fargate, and it's really annoying when you're trying to iterate on something and you have to sit there waiting on "Provisioning..." for 1-2 minutes every time you launch a task. I don't think the control plane is that slow, as EC2 based ECS launches tasks really fast if the images are already cached on the machine.
On the other hand, ECS still seems slow compared to k8s where things are nearly instance unless you're measuring so ECS control plane speed might be part of the issue, too