NAB may have some revolutionary practices driving productivity improvement in a big financial services business. Or NAB may be under-investing its banking businesses even as they generate exceptional revenue (though not profit) growth.Costs fell two half years in a row at NAB's Australian bank and were essentially flat for a seventh half in a row at Bank of New Zealand. This is at a time when inflation is, or was, rising in each of the bank's core markets.One reason for NAB's lower cost at a group level is that numerous compliance projects have largely run their course such as Basel 2 and Sabanes Oxley while various remediation projects, such as new teller systems in Clydesdale Bank and at NAB in Australia, are complete.The NAB management line is that the lower costs do, in fact, reflect productivity gains and are the return for the "transformation" projects that alongside compliance projects have eaten up investment budgets over the last four years.On the revenue side NAB increased income by six per cent in Australia, six per cent in New Zealand, five per cent in Britain and by 22 per cent in nabCapital.In the short term, management does not appear keen to look at much new investment.Chief executive designate Cameron Clyne, in an outline of his own work priorities for the next few months, made clear that he'd asked all the business heads to continue to focus on costs. He also said he wanted innovative measures to drive revenue growth that did not chew up capital.The only explicit investment Clyne foreshadowed was the "replatforming" of the bank, which refers to the replacement of core banking systems that are now due for replacement in all core markets.Clyne said this investment was "once in a generation" so the bank may be deferring investment spend for the major projects that lie ahead. NAB has wasted money on past projects of a similar nature  in Australia earlier this decade.Preserving capital was a second theme to Clyne's priorities. The bank has set a goal of lifting the tier one capital ratio to eight per cent, up from 7.3 per cent after being adjusted (in the bank's favour) to take into account the Basel 2 rules.