It sounds like you were using non-native tools via Rosetta 2 and running x86 containers for your development which of course is slow. That is to be expected. If you want do a fair comparison, tell your Intel Mac to cross compile for ARM all day long and see how slow it becomes. While I appreciate your frustrating experience, it is not typical for developers who have adapted to using native tools.

I would recommend you switch to a native development environment with a modern IDE like Visual Code Studio and develop with native ARM Docker images until you are ready to ship. Then build and test the final x86 image at the end. Docker buildx will allow you to built for multiple architectures at once. Your development will be much faster than on Intel. This is how I develop on my M1 Mac mini and I would never go back to an Intel Mac.

I don't see any reason for using x86 containers on ARM while developing. Especially for Java and Python which are cross-platform. Switch to an ARM based workflow and the M1 will amaze you.