diff --git a/commands/web/behat b/commands/web/behat
index 8888048..82c4044 100755
--- a/commands/web/behat
+++ b/commands/web/behat
@@ -24,5 +24,21 @@ if [ ! -f "bin/behat" ]; then
     composer install
 fi
 
-# Run behat with the provided flags/arguments
+# Signal to PHP-FPM (via shared filesystem) that behat is running, so settings.php
+# can disable modules like captcha and antibot that block automated requests.
+touch /var/www/html/web/.behat_testing
+trap "rm -f /var/www/html/web/.behat_testing" EXIT INT TERM
 bin/behat "$@"
+
+# big_pipe
+# Please use following php code in FeatureContext.php to deal with big_pipe module and failing tests:
+#
+#  /** @BeforeSuite */
+#  public static function disableBigPipe(): void {
+#    \Drupal::service('module_installer')->uninstall(['big_pipe']);
+#  }
+#
+#  /** @AfterSuite */
+#  public static function enableBigPipe(): void {
+#    \Drupal::service('module_installer')->install(['big_pipe']);
+#  }
diff --git a/settings.local.devmode.php b/settings.local.devmode.php
index 0b1a43c..e50ec37 100644
--- a/settings.local.devmode.php
+++ b/settings.local.devmode.php
@@ -191,3 +191,17 @@
 if (file_exists($project_settings)) {
   include $project_settings;
 }
+
+// Prepare the environment for tests. The flag file is created by the
+// ddev behat command and removed on exit, since env vars are not shared
+// between the CLI process and PHP-FPM.
+if (file_exists(DRUPAL_ROOT . '/.behat_testing')) {
+  // Disable captcha during Behat test runs.
+  $config['captcha.captcha_point.user_login_form']['status'] = FALSE;
+  // Enable aggregation
+  $config['system.performance']['css']['preprocess'] = TRUE;
+  $config['system.performance']['js']['preprocess'] = TRUE;
+  // Enable advagg.
+  $config['advagg.settings']['enabled'] = TRUE;
+  // @todo: Decide on cache-bins for tests
+}
diff --git a/settings.local.perfmode.php b/settings.local.perfmode.php
index 79a5113..31504f2 100644
--- a/settings.local.perfmode.php
+++ b/settings.local.perfmode.php
@@ -116,3 +116,17 @@
 if (file_exists($project_settings)) {
     include $project_settings;
 }
+
+// Prepare the environment for tests. The flag file is created by the
+// ddev behat command and removed on exit, since env vars are not shared
+// between the CLI process and PHP-FPM.
+if (file_exists(DRUPAL_ROOT . '/.behat_testing')) {
+  // Disable captcha during Behat test runs.
+  $config['captcha.captcha_point.user_login_form']['status'] = FALSE;
+  // Enable aggregation
+  $config['system.performance']['css']['preprocess'] = TRUE;
+  $config['system.performance']['js']['preprocess'] = TRUE;
+  // Enable advagg.
+  $config['advagg.settings']['enabled'] = TRUE;
+  // @todo: Decide on cache-bins for tests
+}