[perf] in syncPackagesToProfile, only removeExtraItemsFromProfile is mode is not install

Author: savil

devbox.json

@@ -1,7 +1,8 @@
 {
   "packages": [
     "go@latest",
-    "runx:golangci/golangci-lint@latest"
+    "runx:golangci/golangci-lint@latest",
+    "vim@latest"
   ],
   "env": {
     "GOENV": "off",

devbox.lock

@@ -23,6 +23,26 @@
     },
     "runx:golangci/golangci-lint@latest": {
       "resolved": "runx:golangci/golangci-lint@latest"
+    },
+    "vim@latest": {
+      "last_modified": "2023-09-27T18:02:17Z",
+      "resolved": "github:NixOS/nixpkgs/517501bcf14ae6ec47efd6a17dda0ca8e6d866f9#vim",
+      "source": "devbox-search",
+      "version": "9.0.1897",
+      "systems": {
+        "aarch64-darwin": {
+          "store_path": "/nix/store/ljl4mh36bsr1sk7gagyn2v2hsn4b880s-vim-9.0.1897"
+        },
+        "aarch64-linux": {
+          "store_path": "/nix/store/h12mgqn9wgvwlpwsdpxzjjs205awlhyv-vim-9.0.1897"
+        },
+        "x86_64-darwin": {
+          "store_path": "/nix/store/an96p2a9l235cyw0iiq9brqhlwd43jpl-vim-9.0.1897"
+        },
+        "x86_64-linux": {
+          "store_path": "/nix/store/mspb2bklaqssjwpmcicwvsmqrh1ffb96-vim-9.0.1897"
+        }
+      }
     }
   }
 }

examples/development/go/hello-world/trace.out

@@ -305,8 +305,8 @@ func (d *Devbox) profilePath() (string, error) {
 	return absPath, errors.WithStack(os.MkdirAll(filepath.Dir(absPath), 0o755))
 }
 
-// syncPackagesToProfile ensures that all packages in devbox.json exist in the nix profile,
-// and no more.
+// syncPackagesToProfile can ensure that all packages in devbox.json exist in the nix profile,
+// and no more. However, it may skip some steps depending on the `mode`.
 func (d *Devbox) syncPackagesToProfile(ctx context.Context, mode installMode) error {
 	defer debug.FunctionTimer().End()
 	defer trace.StartRegion(ctx, "syncPackagesToProfile").End()
@@ -334,9 +334,12 @@ func (d *Devbox) syncPackagesToProfile(ctx context.Context, mode installMode) er
 	}
 
 	// Second, remove any packages from the nix-profile that are not in the config
-	itemsToKeep, err := d.removeExtraItemsFromProfile(ctx, profileDir, profileItems, packages)
-	if err != nil {
-		return err
+	itemsToKeep := profileItems
+	if mode != install {
+		itemsToKeep, err = d.removeExtraItemsFromProfile(ctx, profileDir, profileItems, packages)
+		if err != nil {
+			return err
+		}
 	}
 
 	// we are done if mode is uninstall