The Call Tree is collated from all the stack snapshots taken during profiling. The Call Tree tab shows a graph in which:
Each parent node represents the caller function, so that the ancestors of each leaf node represent the entire stack. The graph edges are labelled with the time spent in the child call as a percentage of the time spent in the parent call, these times averaged over all the profile data collected.
LispWorks IDE User Guide (Windows version) - 25 Nov 2011