Tried a fusion drive from the interstellar extended mod and did a brachistochrone path towards the mün (pointing at it, burning halfway there, then flipping around and burning the opposite way to slow down)
Took 30 minutes and something like 10k fusion pellets, not that impressive compared to what it's based off (Epstein drive from 'The Expanse') but it's still super impressive compared to what you get in KSP, definitely can't use it for the weeks/months long brachistochrone trajectory shit they do in the TV show but it's still a highly efficient drive