Then there is a suggestion that the time increase gets worse as each package runs.
Can you swap, say, Master1 and Master3 to confirm this?
It would be useful to know whether it's a general degradation, as the numbers suggest, or a package-specific degradation.
If you haven't even tried to resolve your issue, please don't expect the hard-working volunteers here to waste their time providing links to answers which you could easily have found yourself.