This is definitely one way how to do it - but it should be possible to also get fast if you really want to[0][1] + likely also increase human lifespan/hibernate/immortal cyborgs. So there might be whole other class of interstellar ships - much more compact and with its own unique class of moral issues!

[0] https://en.wikipedia.org/wiki/Nuclear_salt-water_rocket

[1] https://en.wikipedia.org/wiki/Antimatter_rocket