More strands in yer bowstring = more mass string weight.
Heavier mass weight strings are slower and more stable. Lighter mass weight strings are faster and less stable. Keeping the center serving and nock point(s) as light weight as possible helps lots (as that's the part of a bowstring that travels the farthest).
Flemish twist strings need lotsa wax as opposed to an endless spun string that needs very little wax. Wax is added string weight.
Strings that stretch/creep more (i.e. - Dacron and Flemish twisted strings) are less consistent than strings that stretch/creep less (i.e. - Dyneema and endless spun strings).
More stretch/spring in yer string = slower arras.
Somewhere in the above text there is a compromise - ya just need to experiment a bit to find what works best for you and yer bow(s).
All my 50-55# hybrid longbows are strung with 14 strand Dyneema'02 endless strings - works best for me.