1. A computer-implemented process for creating an intermediate data structure that maintains at least a portion of a categorized data set, comprising the steps of: selecting a property of a plurality of hierarchically-related objects stored in an original data set; generating a first sliding window portion of the categorized data set by categorizing a first portion of the hierarchically-related objects in the original data set based upon values of the selected property; storing in memory the portion of the categorized data set to create a first intermediate data structure; displaying the first sliding window portion on a display device; in response to a scrolling command, generating a second sliding window portion of the categorized data set by categorizing a second portion of the hierarchially-related objects in the original data set based upon values of the selected property; storing in memory the second sliding window portion of the categorized data set to create a second intermediate data structure; and displaying on the display device the second sliding window portion, such that each intermediate data structure substantially reduces processing time and memory resources required to manipulate the categorized data set.