This works well with big forms due to the time it takes to carry it out so it would complete by then. That is, if the user isn't put off by the size of the form

This works well with big forms due to the time it takes to carry it out so it would complete by then. That is, if the user isn't put off by the size of the form. Small forms not so much and the user would be annoyed. It also penalises users who don't use Javascript. Edit: This fails against a botnet where computers can be told to wait(10) [seconds] after filling form out.