Config cache for system.xml loader: Speed improvement

README.md

@@ -79,7 +79,8 @@ Most important changes will be listed here, all other changes since `19.4.0` can
 
 ### Between Magento 1.9.4.5 and OpenMage 19.x
 
-Bug fixes and PHP 7.x and 8.0 compatibility.
+- bug fixes and PHP 7.x and 8.0 compatibility
+- added config cache for system.xml #1916
 
 ### Between OpenMage 19.x and 20.x
 

app/code/core/Mage/Adminhtml/Model/Config.php

@@ -34,6 +34,15 @@
  */
 class Mage_Adminhtml_Model_Config extends Varien_Simplexml_Config
 {
+    /**
+     * @var string
+     */
+    protected $_cacheId = 'mage_adminhtml_config_system_xml';
+
+    /**
+     * @var Mage_Core_Model_Config_Base
+     */
+    protected $_config;
 
     /**
      * Enter description here...
@@ -80,16 +89,63 @@ public function getTabs()
         return $this->_tabs;
     }
 
+    public function __construct()
+    {
+        $this->_cacheChecksum = null;
+        $this->setCache(Mage::app()->getCache());
+        $this->setCacheTags([Mage_Core_Model_Config::CACHE_TAG]);
+        $usesCache = Mage::app()->useCache('config');
+        if (!$usesCache || !$this->loadCache()) {
+            $this->_config = Mage::getConfig()->loadModulesConfiguration('system.xml')
+                ->applyExtends();
+            if ($usesCache) {
+                $this->saveCache();
+            }
+        }
+    }
+
+    /**
+     * @param array|null $tags
+     * @return $this|Mage_Adminhtml_Model_Config
+     */
+    public function saveCache($tags=null)
+    {
+        if ($this->getCacheSaved()) {
+            return $this;
+        }
+        if (is_null($tags)) {
+            $tags = $this->_cacheTags;
+        }
+        $xmlString = $this->_config->getXmlString();
+        $this->_saveCache($xmlString, $this->getCacheId(), $tags, $this->getCacheLifetime());
+        $this->setCacheSaved(true);
+        return $this;
+    }
+
+    /**
+     * @return bool
+     */
+    public function loadCache()
+    {
+        $xmlString = $this->_loadCache($this->getCacheId());
+        $class = Mage::getConfig()->getModelClassName('core/config_base');
+        $this->_config = new $class();
+        libxml_use_internal_errors(true);
+        if (!empty($xmlString) && $this->_config->loadString($xmlString)) {
+            return true;
+        }
+        libxml_clear_errors();
+        return false;
+    }
+
     /**
      * Init modules configuration
      *
      * @return void
      */
     protected function _initSectionsAndTabs()
     {
-        $config = Mage::getConfig()->loadModulesConfiguration('system.xml')
-            ->applyExtends();
-
+        $config = $this->_config;
         Mage::dispatchEvent('adminhtml_init_system_config', array('config' => $config));
         $this->_sections = $config->getNode('sections');
         $this->_tabs = $config->getNode('tabs');

app/code/core/Mage/Core/etc/config.xml

@@ -122,7 +122,7 @@
             <types>
                 <config translate="label,description" module="core">
                     <label>Configuration</label>
-                    <description>System(config.xml, local.xml) and modules configuration files(config.xml).</description>
+                    <description>System (config.xml, local.xml) and modules configuration files (config.xml, system.xml).</description>
                     <tags>CONFIG</tags>
                 </config>
                 <layout translate="label,description" module="core">

app/locale/en_US/Mage_Core.csv

@@ -433,3 +433,4 @@
 "You will have to log in after you save your custom admin path.","You will have to log in after you save your custom admin path."
 "Your design change for the specified store intersects with another one, please specify another date range.","Your design change for the specified store intersects with another one, please specify another date range."
 "database ""%s""","database ""%s"""
+"System (config.xml, local.xml) and modules configuration files (config.xml, system.xml).","System (config.xml, local.xml) and modules configuration files (config.xml, system.xml)."