Only images that are not available locally will be pulled from .io. In addition, if the download is slow, you can use an accelerator. For example, Alibaba Cloud and DaoCloud provide accelerators

I found that using Alibaba’s accelerator is also very slow. I tried it myself and found that it works by specifying the address directly

version: '2'
services:
dog:

image: hub.c.163.com/public/nginx:1.2.1
ports: 
  - "8080:80"

cat:

image: hub.c.163.com/public/nginx:1.2.1
ports:
  - "8081:80"