GenIDLEST - A scalable parallel computational tool for simulating complex turbulent flows. The application driver is GenIDLEST (Danesh Tafti, Virginia Tech), a computational fluid dynamics application that is being developed and tuned for use on Pentium III, Pentium 4, Xeon, Itanium, and Itanium 2 Linux clusters located at the University of Illinois/NCSA and Virginia Tech. GenIDLEST is used for academic research in addition to use by community and corporate researchers. GenIDLEST development lead Tafti has been working with colleagues to isolate, diagnose, and improve performance-related issues of this application in the Linux cluster environment. Several performance tools have been employed to identify problem areas and to help point the way towards improvement.