diff --git a/main/admin/settings.php b/main/admin/settings.php
index f19a3ed35f..88c44c7e63 100755
--- a/main/admin/settings.php
+++ b/main/admin/settings.php
@@ -95,6 +95,8 @@ $form_search_html = $form_search->returnForm();
 $url_id = api_get_current_access_url_id();
 
 $settings = null;
+$flushSettings = false;
+$cacheAvailable = api_get_configuration_value('apc');
 
 // Build the form.
 if (!empty($_GET['category']) &&
@@ -105,6 +107,7 @@ if (!empty($_GET['category']) &&
     $settings = $settings_array['settings'];
     $settings_by_access_list = $settings_array['settings_by_access_list'];
     $form = generateSettingsForm($settings, $settings_by_access_list);
+    $multipleUrlsEnabled = false;
 
     if ($form->validate()) {
         $values = $form->exportValues();
@@ -113,6 +116,7 @@ if (!empty($_GET['category']) &&
         $un_mark_all = false;
 
         if (api_is_multiple_url_enabled()) {
+            $multipleUrlsEnabled = true;
             if (isset($values['buttons_in_action_right']) &&
                 isset($values['buttons_in_action_right']['mark_all'])
             ) {
@@ -147,6 +151,7 @@ if (!empty($_GET['category']) &&
                                 ];
                                 api_set_setting_simple($params);
                             }
+                            $flushSettings = true;
                         }
                     }
                 }
@@ -208,6 +213,7 @@ if (!empty($_GET['category']) &&
                         access_url = ".intval($url_id)." AND
                         type IN ('checkbox', 'radio') ";
             $res = Database::query($sql);
+            $flushSettings = true;
         }
 
         // Save the settings.
@@ -286,6 +292,7 @@ if (!empty($_GET['category']) &&
                 foreach ($value as $subkey => $subvalue) {
                     $result = api_set_setting($key, 'true', $subkey, null, $url_id);
                 }
+                $flushSettings = true;
             }
         }
 
@@ -299,7 +306,25 @@ if (!empty($_GET['category']) &&
             api_get_utc_datetime(),
             $user_id
         );
-
+        if ($cacheAvailable && $flushSettings) {
+            // Delete the APCu-stored settings array, if present
+            $apcRootVarName = api_get_configuration_value('apc_prefix').'settings_';
+            $apcVarName = $apcRootVarName.$url_id;
+            apcu_delete($apcVarName);
+            if ($multipleUrlsEnabled && $url_id === 1) {
+                // if we are on the main URL of a multi-url portal, we must
+                // invalidate the cache for all other URLs as well as some
+                // main settings span multiple URLs
+                $urls = api_get_access_urls();
+                foreach ($urls as $i => $row) {
+                    if ($row['id'] == 1) {
+                        continue;
+                    }
+                    $apcVarName = $apcRootVarName.$row['id'];
+                    apcu_delete($apcVarName);
+                }
+            }
+        }
         // Add event configuration settings variable to the system log.
         if (is_array($keys) && count($keys) > 0) {
             foreach ($keys as $variable) {
diff --git a/main/inc/lib/api.lib.php b/main/inc/lib/api.lib.php
index 80019cce0d..bce433d876 100755
--- a/main/inc/lib/api.lib.php
+++ b/main/inc/lib/api.lib.php
@@ -6390,6 +6390,25 @@ function api_get_access_url($id, $returnDefault = true)
  */
 function api_get_settings($cat = null, $ordering = 'list', $access_url = 1, $url_changeable = 0)
 {
+    // Try getting settings from cache first (avoids query w/ ~375 rows result)
+    $apcVarName = '';
+    $apcVar = [];
+    $cacheAvailable = api_get_configuration_value('apc');
+    if ($cacheAvailable) {
+        $apcVarName = api_get_configuration_value('apc_prefix').
+            'settings_'.
+            $access_url
+        ;
+        $catName = (empty($cat) ? 'global' : $cat);
+
+        if (apcu_exists($apcVarName)) {
+            $apcVar = apcu_fetch($apcVarName);
+            if (!empty($apcVar[$catName]) && !empty($apcVar[$catName][$ordering]) && isset($apcVar[$catName][$ordering][$url_changeable])) {
+                return $apcVar[$catName][$ordering][$url_changeable];
+            }
+        }
+    }
+    // Could not find settings in cache (or already expired), so query DB
     $table = Database::get_main_table(TABLE_MAIN_SETTINGS_CURRENT);
     $access_url = (int) $access_url;
     $where_condition = '';
@@ -6417,6 +6436,18 @@ function api_get_settings($cat = null, $ordering = 'list', $access_url = 1, $url
     }
     $result = Database::store_result($result, 'ASSOC');
 
+    if ($cacheAvailable) {
+        // If we got here, it means cache is available but the settings
+        // were not recently stored, so now we have them, let's store them
+        if (empty($apcVar[$catName])) {
+            $apcVar[$catName] = [];
+        }
+        if (empty($apcVar[$catName][$ordering])) {
+            $apcVar[$catName][$ordering] = [];
+        }
+        $apcVar[$catName][$ordering][$url_changeable] = $result;
+        apcu_store($apcVarName, $apcVar, 600);
+    }
     return $result;
 }