From email:

I wish to inform you that I've just released the 4.5.020 version that
includes tons of bugfixes and performance improvements over the current
version distributed with Moodle.

You can find more information on http://www.tcpdf.org

To keep informed on new TCPDF releases you can subscribe to:
http://sourceforge.net/project/filemodule_monitor.php?filemodule_id=140403

Please don't hesitate to contact me for further information.

Sincerely,

–

Nicola Asuni
the author of the TCPDF library used on Moodle to produce PDF documents