haifeng:

It is like either use a large image, or install a large package on startup.


The difference Is that with the postcreatecommand you have this overhead/lag for every container you launch instead after the image/layer is downloaded/cached the first time you don’t have this overhead anymore.
Partially this advantage is invalidated if we ask to contributors to update tf-nightly or a tf-nightly layer in the image every single day.