Lazily evaluate the properties

Author: jsumners

lib/internal/modules/esm/initialize_import_meta.js

@@ -66,10 +66,20 @@ function resolveModuleMeta(url) {
     return { __dirname: undefined, __filename: undefined };
   }
 
-  const filePath = fileURLToPath(url);
+  // We return an object with getters to reduce memory usage in modules that
+  // do not use these properties, i.e. most modules don't need the values
+  // to be resolved until the first time the property is accessed.
+  let filePath;
+  let dirPath;
   return {
-    __dirname: dirname(filePath),
-    __filename: filePath,
+    get __dirname() {
+      return dirname(filePath ??= fileURLToPath(url));
+    },
+    get __filename() {
+      filePath ??= fileURLToPath(url);
+      dirPath ??= dirname(filePath);
+      return filePath;
+    },
   };
 }