Recently Vector space from USA has said that propylene is a better choice of fuel than RP-1. See Ars Technica's After a decade of testing, propylene rocket fuel may be ready for prime time
Why is propylene a better fuel than RP-1? At what density is it used for that purpose?
edit: while some level of comparison can be found in answer(s) to Vector-R's LP-1 and -2 engines use liquid propylene as fuel with LOX, advantages and distinctions from kerosene?, I'd like to know more details on how the two fuels compare quantitatively.
I tried to check the density of propylene on internet but it is less dense than RP-1 then how does it provide more performance, and roughly how large is this difference in performance?