Even if you configure the Profiler to profile all the known functions of an application, it is possible that less than 100% of the time is spent monitoring the top function. This is because an internal system function could be on the top of the stack at the time of the interrupt.
If you configure the Profiler to omit certain functions then these will not be displayed in the Results area, and so the display may not match what you expect from your source code.
LispWorks IDE User Guide (Macintosh version) - 25 Nov 2011