1. In a system to generate personalized recommendations with improved utilization of system hardware resources by using localized regularization, a method implemented by one or more computing devices, the method comprising: obtaining, by the one or more computing devices, known values for each item in a first subset of a set of items, the known values corresponding to one of multiple users of the system; identifying, by the one or more computing devices, a second subset of the set of items, each item in the second subset having an unknown value; generating, by the one or more computing devices for each item in the second item subset, a value for the item based on localized regularization that is personalized to the user; and taking, by the one or more computing devices based on the generated values for the items in the second item subset, one or more actions personalized to the user.