diff --git a/src/phpbrowscap/Browscap.php b/src/phpbrowscap/Browscap.php
index 071db06..9aa28df 100644
--- a/src/phpbrowscap/Browscap.php
+++ b/src/phpbrowscap/Browscap.php
@@ -573,6 +573,9 @@ public function updateCache()
 
             $this->_browsers[] = $browser;
         }
+        
+        // reducing memory usage by unsetting $tmp_user_agents
+        unset($tmp_user_agents);
 
         foreach ($tmp_patterns as $pattern => $pattern_data) {
           if (is_int($pattern_data)) {