Those docker images were not light, and the max 8GB RAM on the MacBook didn't help, but emulation was not the problem, this was x64 on x64. It's just the Intel m CPUs are just slow, here's the MacBook compared to my Mac Mini:
https://browser.geekbench.com/v4/cpu/compare/12140024?baseli...
and here versus the 2013 MacBook Pro that I normally used instead for development:
https://browser.geekbench.com/v4/cpu/compare/1965771?baselin...
You should run arm64 images on your M1 Mac, in fact at my company we are shifting all the workloads we can to Graviton2 on AWS because of the substantial cost savings, but yes, porting is not a completely trivial exercise and migrating our development environment over to Docker on M1 is still work in progress, and in the meantime we have scrounged up all the Intel MacBook Pros in the company and reserved them for developers.
Many people use/need Docker, but of course it requires a Linux kernel (often running in a hypervisor if you're running macOS.) VMs can easily eat up a lot of resources, especially memory. Alternately a VM without enough memory will also perform abysmally.
I've also heard complaints about poor performance (vs. native Linux or even WSL on x86 hardware) of x86 Docker images running in emulation on an M1 MacBook Air.