if you want fast builds it's worth spinning up a buildkit server on a beefy dedicated server.

docker/nerdctl only transfers the context, everything else is cached on the builder. it's very useful for monorepos (where you usually want to build and tag images for every tested commit)

and the builder directly pushes the images/tags/layers to the registry. (which can be just a new tag for already existing layer.)

a noop job is about 2 sec on GitLab CI this way.

i haven't looked into setting up a buildkit server. would it be easier to just attach an ebs volume?

you mean run an EC2 instance with EBS as buildkit server storage dir?

sure, it should work nicely. (I just prefer the local disk, it's just a cache after all.)