There were some pandas data manipulations at a few stages of the calibration process which were quite inefficient, with exponential increases in processing time as camera count increased. With 5 or 6 cameras, it was manageable, but with 10+ was clearly not practical.
This pandas code was refactored (hat tip to claude) and is now substantially faster. If someone had issues with slow calibrations in the past, my hope is that v0.6 will be a much better experience.