dave - go back over the technique with him once more, except this time at normal operating speed and get him to show you the same technique at the same speed. He should manage it without any probs. Don't forget, the important thing is that he is doing the job right and that speed, especially with trad tools is something that can take a little while to get up to speed with.
He is probably a little unsure of the quality of his own work so I would tell him not to bother checking over the work and that if there are any problems the customer will let you know and for him not to worry about it.
with a little bit of persuasion he'll speed up soon. well you would like to think so.