The tote facility at Betfair has a clock that is usually a minute or so behind REAL Time.
Many times I've lost good winners because of that darn clock made me late getting my last minute bet on.
I have saved money on occasions as well, but the terrible feeling of not backing a winner is terrible and pretty much ruins the whole day.

The Betfair people said they have no control over when the race starts, but I didn't query them about that.
The people that man the query lines are just people and not well trained in the information.