Figures from the Current Account Switch Service (Cass) show it has redirected more than 85.5 million payments from the old accounts of customers who have switched to their new ones.
Before, it could take as long as a month to "ditch and switch" providers.
A survey from Cass of 2,300 people also found that 37 per cent of under-25s leave their old account open when getting a new one, compared with only 17 per cent of over-35s.
People who do leave their old accounts open do not benefit from Cass's switch guarantee.
The guarantee means a customer's new bank takes care of closing their old account, moving their balance and switching their payments.
Figures provided to Cass by banks and building societies also suggest that, between April 1 and June 30 2019, Nationwide Building Society, NatWest and HSBC were among the biggest winners in terms of people switching to them.
Many people also switched to challenger brands. Digital banks Monzo and Starling Bank also made net gains, as did ethical bank Triodos.
Barclays, Halifax, Lloyds, Royal Bank of Scotland, Santander and TSB were among those who made net customer losses.
The figures only cover customers who switched using the full Cass service with the guarantee and therefore do not include switches made outside the service.