diff --git a/configs/development.ini b/configs/development.ini
--- a/configs/development.ini
+++ b/configs/development.ini
@@ -290,6 +290,9 @@ instance_id =
 ## egg:rhodecode-enterprise-ce#crowd
 #rhodecode.auth_plugin_fallback = egg:rhodecode-enterprise-ce#rhodecode
 
+## Flag to control loading of legacy plugins in py:/path format
+auth_plugin.import_legacy_plugins = true
+
 ## alternative return HTTP header for failed authentication. Default HTTP
 ## response is 401 HTTPUnauthorized. Currently HG clients have troubles with
 ## handling that causing a series of failed authentication calls.
diff --git a/configs/production.ini b/configs/production.ini
--- a/configs/production.ini
+++ b/configs/production.ini
@@ -265,6 +265,9 @@ instance_id =
 ## egg:rhodecode-enterprise-ce#crowd
 #rhodecode.auth_plugin_fallback = egg:rhodecode-enterprise-ce#rhodecode
 
+## Flag to control loading of legacy plugins in py:/path format
+auth_plugin.import_legacy_plugins = true
+
 ## alternative return HTTP header for failed authentication. Default HTTP
 ## response is 401 HTTPUnauthorized. Currently HG clients have troubles with
 ## handling that causing a series of failed authentication calls.
diff --git a/rhodecode/config/middleware.py b/rhodecode/config/middleware.py
--- a/rhodecode/config/middleware.py
+++ b/rhodecode/config/middleware.py
@@ -266,7 +266,6 @@ def includeme(config):
         config.include('rhodecode.integrations')
 
     if load_all:
-        from rhodecode.authentication import discover_legacy_plugins
         # load CE authentication plugins
         config.include('rhodecode.authentication.plugins.auth_crowd')
         config.include('rhodecode.authentication.plugins.auth_headers')
@@ -277,7 +276,9 @@ def includeme(config):
         config.include('rhodecode.authentication.plugins.auth_token')
 
         # Auto discover authentication plugins and include their configuration.
-        discover_legacy_plugins(config)
+        if asbool(settings.get('auth_plugin.import_legacy_plugins', 'true')):
+            from rhodecode.authentication import discover_legacy_plugins
+            discover_legacy_plugins(config)
 
     # apps
     if load_all: