Why use Docker images in production when already have VMs?

I am doing research on which is the most efficient way for serving a production app from a cloud hosting provider like DigitalOcean using linux as server platform. DigitalOcean provides VMs - called droplets. Common sense would be that the best way is to just deploy the app as is in the VM (droplet) provided. Docker containers surely bring an overhead that translates to slower response from the deployed app. I am not aware of any optimizations done by the cloud hosting providers to the docker containers running inside VMs. Considering that the VMs can be configured with scripts to be identical as the Docker containers, does it make any sense to use Docker in production?