diff -u b/includes/common.inc b/includes/common.inc
--- b/includes/common.inc
+++ b/includes/common.inc
@@ -5538,35 +5538,19 @@
     watchdog('cron', 'Attempting to re-run cron while it is already running.', array(), WATCHDOG_WARNING);
   }
   else {
-    $queue_name_previous = '';
-
     // Make sure every queue exists. There is no harm in trying to recreate an
     // existing queue.
     foreach ($queues as $queue_name => $info) {
-      // Log a message saying that the queue started.
-      watchdog('cron', 'Starting execution of queue @queue_name.', array(
-        '@queue_name' => $queue_name,
-      ), WATCHDOG_NOTICE);
-
-      timer_start('cron_queue_' . $queue_name);
       DrupalQueue::get($queue_name)->createQueue();
-      timer_stop('cron_queue_' . $queue_name);
-
-      // Log a message saying that the queue ended.
-      watchdog('cron', 'Execution of queue @queue_name took @time.', array(
-        '@queue_name' => $queue_name,
-        '@time' => timer_read('cron_queue_' . $queue_name) . 'ms',
-      ), WATCHDOG_NOTICE);
     }
 
-    $module_previous = '';
-
     // Iterate through the modules calling their cron handlers (if any):
     foreach (module_implements('cron') as $module) {
-      // Log a message saying that the cron event started.
-      watchdog('cron', 'Starting execution of @module_cron().', array('@module' => $module), WATCHDOG_NOTICE);
-
-      timer_start('cron_' . $module);
+      if (variable_get('cron_logging_enabled', TRUE)) {
+        // Log a message saying that the cron event started.
+        watchdog('cron', 'Starting execution of @module_cron().', array('@module' => $module), WATCHDOG_NOTICE);
+        timer_start('cron_' . $module);
+      }
 
       // Do not let an exception thrown by one module disturb another.
       try {
@@ -5576,13 +5560,14 @@
         watchdog_exception('cron', $e);
       }
 
-      timer_stop('cron_' . $module);
-
-      // Log a message saying that the cron event ended.
-      watchdog('cron', 'Execution of @module_cron() took @time.', array(
-        '@module' => $module,
-        '@time' => timer_read('cron_' . $module) . 'ms',
-      ), WATCHDOG_NOTICE);
+      if (variable_get('cron_logging_enabled', TRUE)) {
+        timer_stop('cron_' . $module);
+        // Log a message saying that the cron event ended.
+        watchdog('cron', 'Execution of @module_cron() took @time.', array(
+          '@module' => $module,
+          '@time' => timer_read('cron_' . $module) . 'ms',
+        ), WATCHDOG_NOTICE);
+      }
     }
 
     // Record cron time.
diff -u b/modules/dblog/dblog.test b/modules/dblog/dblog.test
--- b/modules/dblog/dblog.test
+++ b/modules/dblog/dblog.test
@@ -147,6 +147,15 @@
     // The number of log entries created.
     $logs_count = $current_id - $last_id;
     $this->assertEqual($logs_count, $cron_logs_expected, format_string('Cron added @count of @expected new log entries', array('@count' => $logs_count, '@expected' => $cron_logs_expected)));
+
+    // Test the number of entries with "cron_logging_enabled" disabled.
+    variable_set('cron_logging_enabled', FALSE);
+    $last_id = db_query('SELECT MAX(wid) FROM {watchdog}')->fetchField();
+    $this->cronRun();
+    $current_id = db_query('SELECT MAX(wid) FROM {watchdog}')->fetchField();
+
+    // Only one final "cron is finished" message should be logged.
+    $this->assertEqual($current_id - $last_id, 1, format_string('Cron added one new log entry.'));
   }
 
   /**
only in patch2:
unchanged:
--- a/sites/default/default.settings.php
+++ b/sites/default/default.settings.php
@@ -881,3 +881,12 @@
  * prevention and revert to the original behaviour.
  */
 # $conf['javascript_use_double_submit_protection'] = FALSE;
+
+/**
+ * Cron logging.
+ *
+ * By default drupal_cron_run() will log each execution of hook_cron() together
+ * with the execution time. Set this variable to FALSE in order to opt out of
+ * this behaviour.
+ */
+# $conf['cron_logging_enabled'] = TRUE;