Ran ap_verify with the full CI-HiTS2015 dataset used as processing (6 ccds worth of data). A/B-ed the current fitter with a simple matrix solver. The two files are attached as outputStack.png (for the current weekly version 30) and a simpler flux fitting model in outputSimpleFit.png.
Looking at the percentages, the new fitter reduces the time spent in _`set_flux_stats` from 7.96% of processing time to 4.53% of processing time. This reduces the time spent in association.run from 9.77% to 6.40%.
I've added a this quick fix to a branch associated with this ticket.