[yusefnapora]

You don't actually need to rebuild the world, just the part that changed. It's rare to have other nix derivations depend on the dotfiles directly, so changes don't "cascade" to the rest of the system. I just timed how long it takes to rebuild my system after changing my neovim config and it's ~30 seconds. Which sounds like a lot compared to the zero seconds it takes to edit the config without nix, but it's fast enough that I personally don't mind.

Some people do use nix just for their system config and manage their dotfiles separately, but for me it's simpler to just have one system that installs the software I want and configures it the way I like it, rather than two things I'd need to keep in sync with each other.