diff --git a/nixos/modules/services/misc/nix-gc.nix b/nixos/modules/services/misc/nix-gc.nix
index 034b044fbafe..d2a7f0bf433e 100644
--- a/nixos/modules/services/misc/nix-gc.nix
+++ b/nixos/modules/services/misc/nix-gc.nix
@@ -88,6 +88,8 @@ in
       script = "exec ${config.nix.package.out}/bin/nix-collect-garbage ${cfg.options}";
       serviceConfig.Type = "oneshot";
       startAt = lib.optionals cfg.automatic cfg.dates;
+      # do not start and delay when switching
+      restartIfChanged = false;
     };
 
     systemd.timers.nix-gc = lib.mkIf cfg.automatic {
diff --git a/nixos/modules/services/misc/nix-optimise.nix b/nixos/modules/services/misc/nix-optimise.nix
index 3581b95ce18a..ad12e9a83d2f 100644
--- a/nixos/modules/services/misc/nix-optimise.nix
+++ b/nixos/modules/services/misc/nix-optimise.nix
@@ -69,6 +69,8 @@ in
         unitConfig.ConditionPathIsReadWrite = "/nix/var/nix/daemon-socket";
         serviceConfig.ExecStart = "${config.nix.package}/bin/nix-store --optimise";
         startAt = lib.optionals cfg.automatic cfg.dates;
+        # do not start and delay when switching
+        restartIfChanged = false;
       };
 
       timers.nix-optimise = lib.mkIf cfg.automatic {