KiwiSaver schemes with a strong bias to shares and listed property were the best performers in 2012 but are not expected to repeat their double-digit returns this year.
Morningstar's quarterly KiwiSaver Performance Survey shows Milford had two top-performing KiwiSaver schemes last year with 27%, while Aon KiwiSaver Russell, Brook and Fisher Funds schemes also rated well.
It says while shares and listed property showed double digit growth, fixed interest returns were lacklustre.
But Morningstar's co-head of fund research Chris Douglas says KiwiSaver investors tempted to switch to the top performing funds should be wary.
Mr Douglas says the high New Zealand dollar is starting to have an effect on the schemes.
KiwiSaver funds have grown from $954 million to $13.65 billion in five years with ASB and OnePath commanding nearly half the assets between them.