Beef up linux builder

I need a bigger linux builder to build another linux...

modules/base/default.nix

@@ -9,8 +9,6 @@
     package = pkgs.nix;
 
     settings = {
-      auto-optimise-store = true;
-
       experimental-features = [
         "nix-command"
         "flakes"
@@ -35,6 +33,8 @@
         "larstvei.cachix.org-1:mJq98qeTBnm2xNNibn2BEwN1ggi6uQg+5hWASdG1Vys="
       ];
     };
+
+    optimise.automatic = true;
   };
 
   environment.systemPackages = [

modules/darwin/default.nix

@@ -4,7 +4,20 @@
     ../homebrew
   ];
 
-  nix.linux-builder.enable = true;
+  nix.linux-builder = {
+    enable = true;
+    ephemeral = true;
+    maxJobs = 4;
+    config = {
+      virtualisation = {
+        darwin-builder = {
+          diskSize = 200 * 1024;
+          memorySize = 8 * 1024;
+        };
+        cores = 6;
+      };
+    };
+  };
 
   system = {
     stateVersion = 4;