Aspects of the invention provide a solution for determining a storage location for a data item from among a set of persistent storage locations having varying access speeds. Each data item is associated with a score that is based on the frequency with which the data item has been accessed, as well as possible other factors such as open time and/or close time of the data item, the amount of data in the data item, the period from the last time the data item was closed to the next time that the data item is opened and/or the total amount of data in the data item. Data items with high scores relative to other data items are assigned to faster access storage location while data items with lower scores are assigned to slower access storage locations.