If you benefit from web2py hope you feel encouraged to pay it forward by contributing back to society in whatever form you choose!
Book quote: "...If you use two asterisks (**), the MODELs will not be executed. This is the recommended way of calling, as it has less overhead and avoids potential locking problems. ..."
This approach should be used for enhancing the task's performance (if you are not doing db update in background of course)
(commented by spametki)
How to write time scheduled tasks with web2py built-in cron