diff --git a/dwds/test/integration/fixtures/context.dart b/dwds/test/integration/fixtures/context.dart
index ebf7bb654..c799a1381 100644
--- a/dwds/test/integration/fixtures/context.dart
+++ b/dwds/test/integration/fixtures/context.dart
@@ -252,11 +252,11 @@ class TestContext {
       var filePathToServe = project.filePathToServe;
 
       // Start the HTTP server and save its used port.
-      final httpServer = await startHttpServer('localhost');
+      final httpServer = await startHttpServer('127.0.0.1');
       _port = httpServer.port;
 
       final reloadedSourcesUri = Uri.parse(
-        'http://localhost:$_port/${WebDevFS.reloadedSourcesFileName}',
+        'http://127.0.0.1:$_port/${WebDevFS.reloadedSourcesFileName}',
       );
 
       switch (testSettings.compilationMode) {
@@ -332,7 +332,7 @@ class TestContext {
 
             if (testSettings.enableExpressionEvaluation) {
               ddcService = ExpressionCompilerService(
-                'localhost',
+                '127.0.0.1',
                 _port!,
                 verbose: testSettings.verboseCompiler,
                 sdkConfigurationProvider: sdkConfigurationProvider,
@@ -518,7 +518,7 @@ class TestContext {
 
             if (testSettings.enableExpressionEvaluation) {
               ddcService = ExpressionCompilerService(
-                'localhost',
+                '127.0.0.1',
                 _port!,
                 verbose: testSettings.verboseCompiler,
                 sdkConfigurationProvider: sdkConfigurationProvider,
@@ -595,7 +595,7 @@ class TestContext {
       // listeners in DWDS or `main` is run.
       final tabConnectionCompleter = Completer<void>();
       final appConnectionCompleter = Completer<void>();
-      final connection = ChromeConnection('localhost', debugPort);
+      final connection = ChromeConnection('127.0.0.1', debugPort);
 
       // TODO(srujzs): In the case of the frontend server, it doesn't make sense
       // that we initialize a new HTTP server instead of reusing the one in
@@ -632,8 +632,8 @@ class TestContext {
       });
 
       _appUrl = basePath.isEmpty
-          ? 'http://localhost:$port/$filePathToServe'
-          : 'http://localhost:$port/$basePath/$filePathToServe';
+          ? 'http://127.0.0.1:$port/$filePathToServe'
+          : 'http://127.0.0.1:$port/$basePath/$filePathToServe';
 
       if (testSettings.launchChrome) {
         await _webDriver?.get(appUrl);
@@ -834,7 +834,7 @@ class TestContext {
   /// Returns a handler for build runner + DDC AMD module system.
   Handler _createBuildRunnerAmdAssetHandler(int assetServerPort) {
     return proxyHandler(
-      'http://localhost:$assetServerPort/${project.directoryToServe}/',
+      'http://127.0.0.1:$assetServerPort/${project.directoryToServe}/',
       client: client,
     );
   }
@@ -848,7 +848,7 @@ class TestContext {
   ///   `project.directoryToServe`.
   Handler _createBuildRunnerDdcLibraryBundleAssetHandler(int assetServerPort) {
     final entrypointProxy = proxyHandler(
-      'http://localhost:$assetServerPort/${project.directoryToServe}/',
+      'http://127.0.0.1:$assetServerPort/${project.directoryToServe}/',
       client: client,
     );
 
diff --git a/dwds_test_common/lib/test_sdk_configuration.dart b/dwds_test_common/lib/test_sdk_configuration.dart
index c6fabc016..3a985e1c5 100644
--- a/dwds_test_common/lib/test_sdk_configuration.dart
+++ b/dwds_test_common/lib/test_sdk_configuration.dart
@@ -7,6 +7,7 @@ import 'dart:io';
 import 'package:dwds/expression_compiler.dart';
 import 'package:dwds/sdk_configuration.dart';
 import 'package:logging/logging.dart';
+import 'package:path/path.dart' as p;
 
 import 'sdk_asset_generator.dart';
 import 'test_sdk_layout.dart';
@@ -58,6 +59,29 @@ class TestSdkConfigurationProvider extends SdkConfigurationProvider {
     }
 
     try {
+      final cacheDirName =
+          'dwds_sdk_cache_${ddcModuleFormat.name}_$canaryFeatures';
+      final cacheDir = Directory(
+        p.join(Directory.systemTemp.path, cacheDirName),
+      );
+      final cacheJsFile = File(p.join(cacheDir.path, 'dart_sdk.js'));
+      final cacheJsMapFile = File(p.join(cacheDir.path, 'dart_sdk.js.map'));
+
+      final targetJsPath = ddcModuleFormat == ModuleFormat.amd
+          ? sdkLayout.amdJsPath
+          : sdkLayout.ddcJsPath;
+      final targetJsMapPath = ddcModuleFormat == ModuleFormat.amd
+          ? sdkLayout.amdJsMapPath
+          : sdkLayout.ddcJsMapPath;
+
+      if (cacheJsFile.existsSync() && cacheJsMapFile.existsSync()) {
+        _logger.info('Found cached SDK assets in ${cacheDir.path}');
+        await File(targetJsPath).create(recursive: true);
+        await File(targetJsMapPath).create(recursive: true);
+        await cacheJsFile.copy(targetJsPath);
+        await cacheJsMapFile.copy(targetJsMapPath);
+      }
+
       final assetGenerator = SdkAssetGenerator(
         sdkLayout: sdkLayout,
         canaryFeatures: canaryFeatures,
@@ -66,6 +90,20 @@ class TestSdkConfigurationProvider extends SdkConfigurationProvider {
       );
 
       await assetGenerator.generateSdkAssets();
+
+      if (!cacheJsFile.existsSync() || !cacheJsMapFile.existsSync()) {
+        _logger.info('Caching SDK assets in ${cacheDir.path}');
+        await cacheDir.create(recursive: true);
+        final tempJs = File(p.join(cacheDir.path, 'dart_sdk.js.tmp'));
+        final tempJsMap = File(p.join(cacheDir.path, 'dart_sdk.js.map.tmp'));
+
+        await File(targetJsPath).copy(tempJs.path);
+        await File(targetJsMapPath).copy(tempJsMap.path);
+
+        await _safeRename(tempJs, cacheJsFile.path);
+        await _safeRename(tempJsMap, cacheJsMapFile.path);
+      }
+
       return TestSdkLayout.createConfiguration(sdkLayout);
     } catch (e, s) {
       _logger.severe('Failed generate missing assets', e, s);
@@ -86,4 +124,12 @@ class TestSdkConfigurationProvider extends SdkConfigurationProvider {
       }
     }
   }
+
+  Future<void> _safeRename(File from, String to) async {
+    try {
+      await from.rename(to);
+    } on FileSystemException {
+      // Ignore if rename fails (e.g. file exists or busy on Windows).
+    }
+  }
 }