diff --git a/src/phpbrowscap/Browscap.php b/src/phpbrowscap/Browscap.php
index 17e0be78..65d4986d 100644
--- a/src/phpbrowscap/Browscap.php
+++ b/src/phpbrowscap/Browscap.php
@@ -592,6 +592,9 @@ 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)) {
                 $this->_patterns[$pattern] = $pattern_data;