solution with parameter

samples/react-calendar-feed/gulpfile.js

@@ -4,51 +4,42 @@ const gulp = require('gulp');
 const build = require('@microsoft/sp-build-web');
 build.addSuppression(`Warning - [sass] The local CSS class 'ms-Grid' is not camelCase and will not be type-safe.`);
 
+let needIESupport = true;
+if(!!process.argv && process.argv.length >0) {
+  needIESupport = process.argv.findIndex(item => '--noie11' === item.toLowerCase()) !=-1 ;
+}
+
+
+if(needIESupport){
+  process.stdout.write(`Using babel-loader to support IE11 \n`);
+  build.configureWebpack.mergeConfig({
+    additionalConfiguration: (generatedConfiguration) => {
+      generatedConfiguration.module.rules.push({
+        test: /\.js$/,
+       exclude: /node_modules\/(?!(rss-paser))/,
+        use: {
+          loader: 'babel-loader',
+          options: {
+            presets: [
+              ["@babel/preset-env",
+                {
+                  targets: {
+                    "ie": "11"
+                  }
                   
-build.configureWebpack.mergeConfig({
-  additionalConfiguration: (generatedConfiguration) => {
-    generatedConfiguration.module.rules.push({
-      test: /\.js$/,
-     exclude: /node_modules\/(?!(rss-paser|@babel))/,
-      use: {
-        loader: 'babel-loader',
-        options: {
-          presets: [
-            ["@babel/preset-env",
-              {
-                targets: {
-                  "ie": "11"
                 }
-              }
+              ]
             ]
-          ]
+          }
         }
-      }
-    });
-
-    return generatedConfiguration;
-  }
-});
-
-/* 
-Show current Webpack configuration
-*/
-/*
-build.configureWebpack.mergeConfig({
-  additionalConfiguration: (generatedConfig) => {
-    console.log('<webpack.config type="object">');
-    console.log(generatedConfig);
-    console.log('</webpack.config>');
-
-    console.log('<webpack.config type="string">');
-    console.log(JSON.stringify(generatedConfig));
-    console.log('</webpack.config>');
-
-    return generatedConfig;
-  }
-});
-*/
+      });
   
+      return generatedConfiguration;
+    }
+  });
+} else {
+  process.stdout.write(`No IE11 Support webpack will be 5 times faster \n`);
+}
 
 
 build.initialize(gulp);