A lot of Nix projects end up with their own binary cache (also known as a “substituter”). Nix can be quite slow when it’s configured to use many project-specific substituters, because it queries them all when checking if it needs to build a derivation. In a specific project, most of the other substituters Nix knows about are irrelevant, and querying them is wasted effort. My solution is to only enable https://cache.nixos.org globally, and to selectively enable other substituters while I...
