Forums Scripts & Popups Which one can be perform faster

i'm also confius about this kind structure of code..

which on can be perform faster
e.g :
var %x

i) if (x==1) set %a = x
if (x==2) set %a = x
if (x==3) set %a = x

ii) if (x==1 || x==2 || x==3) set %a = x

iii) or $iff is proper tu use