Changes for 6.x resulted in the load time information getting squeezed out of view when playing with reduced size windows. Build time was also squeezed out.
I vaguely remember the base load time being about 2 days per 5,000 tons of freight capacity. Cargo modules provide a 5x loading multiplier per module, so a basic 25,000 ton cargo freighter should take 10 days to load with zero cargo handling, 2 days to load with one cargo handling module, 1 day with two cargo handling modules, 16 hours with three, 12 hours with four, etc.