Bankwest has ceased to be a millstone for Commonwealth Bank and is now producing a credible profit, with much of the past strife with asset quality now resolved.The bank said cash earnings growth at Bankwest for the half year to December 2013 rose 37 per cent, to A$353 million. Its return on assets was 0.95 per cent, 15 basis points less than the group ROA but a rise of 25 basis points over a year.The loan impairment expense was only $5 million in the half, down from $86 million a year before.CBA said there was "a continued run-off of the troublesome loan book in Bankwest, resulting in reduced requirements for provisions."David Craig, the bank's chief financial officer, said: "Clearly, we have room to focus on building and renewing the [Bankwest] business bank in [business lending]."Home loan growth was seven per cent, which is well above system and better than for the CBA group.