anchor.diff:      });
     };
   
  +  # Disabling optimization for cardano-sl packages will
  +  # return a build ~20% faster (measured in DEVOPS-1032).
  +  fasterBuildOverlay = self: super: {
  +    mkDerivation = args: super.mkDerivation (args // optionalAttrs (localLib.isCardanoSL args.pname) {
  +      configureFlags = (args.configureFlags or []) ++ [ "--ghc-options=-O0" ];
  +    });
  +  };
  +
     dontCheckOverlay = self: super: {
       mkDerivation = args: super.mkDerivation (args // {
         doCheck = false;
  
positive.code: , enablePhaseMetrics ? true
  , allowCustomConfig ? true
  , useStackBinaries ? false
  }:
  
  with pkgs.lib;
  
negative.code:       ++ optional enablePhaseMetrics metricOverlay
        ++ optional enableBenchmarks benchmarkOverlay
        ++ optional enableDebugging debugOverlay
        ++ optional forceDontCheck dontCheckOverlay
        ++ optional fasterBuild fasterBuildOverlay;
  
    cardanoPkgs = builtins.foldl' (pkgs: overlay: pkgs.extend overlay) cardanoPkgsBase activeOverlays;
    connect = let
  