The Linac Coherent Light Source (LCLS) at the SLAC National Accelerator Laboratory is an X-ray Free Electron Laser (X-FEL) facility enabling scientists to take snapshots of single macromolecules to study their structure and dynamics. A major LCLS upgrade, LCLS-II, will bring the repetition rate of the X-ray source from 120 to 1 million pulses per second and exascale High Performance Computing (HPC) capabilities will be required for the data analysis to keep up with the future data taking rates. We present here a Python application for Fluctuation X-ray Scattering (FXS), an emerging technique for analyzing biomolecular structure from the angular correlations of FEL diffraction snapshots with one or more particles in the beam. This FXS application for experimental data analysis is being developed to run on supercomputers in near real-time while an experiment is taking place. We discuss how we accelerated the most compute intensive parts of the application and how we used Pygion, a Python interface for the Legion taskbased programming model, to parallelize and scale the application.