Do you have a one cup coffee maker? My friend Laura taught me this trick: dispense a coffee cup of water (take any pods out first!) to speed up cooking! It started with peas...she counseled me to take some peas and put them in a coffee mug. Next dispense a cup of hot water and place that filled mug into the microwave. Using water that's already hot saved minutes!
I decide to expand this idea and try it was boiling water on the stove...same effect! Boiling my mashed potato water (instant this particular eve) was super duper fast since I started with super hot water already. Try it!