buildQueries produces ~300 trivial mkdir+symlink derivations (one per language) under passthru.queries / withAllGrammars. They're not on cache.nixos.org since release.nix doesn't recurse into passthru.queries and the only Hydra job that builds them (passthru.tests.check-queries) doesn't keep them in its runtime closure. With remote builders configured, each one round-trips over the network for a build that's faster than the SSH handshake. Use runCommandLocal so they build on the local machine and skip the guaranteed-miss cache queries.