PHP Safe Mode/open_basedir - lstat performance problem

Realpath cache is disabled if safe_mode or open_basedir are set. This dramatically reduce performance of PHP Engine and this behavior can bring a server to its knees. Especially because there is a lack of documentation!

Looking at source code main/main.c of PHP engine 5.2.13 you can see:

1292:  /* Disable realpath cache if safe_mode or open_basedir are set 
*/
                if (PG(safe_mode) || (PG(open_basedir) && *PG(open_basedir))) {
                        CWDG(realpath_cache_size_limit) = 0;
                }

1769: /* Disable realpath cache if safe_mode or open_basedir are set */
        if (PG(safe_mode) || (PG(open_basedir) && *PG(open_basedir))) {
                CWDG(realpath_cache_size_limit) = 0;
        }

Please refer to: http://bugs.php.net/bug.php?id=52312