As long as the commands don't produce echo outputs itself (which can be silenced - thats what the prefix is meant for), it's the same performance.
If you have doubts - run your own test, like:
alias nonsilenced {
var %n = 1, %start = $ticks
while (%n <= 50000) {
var %a = $ticks
noop
inc %n
}
echo -a nonsilenced $calc($ticks - %start) ticks
}
alias silenced {
var %n = 1, %start = $ticks
.while (%n <= 50000) {
.var %a = $ticks
.noop
.inc %n
}
echo -a silenced $calc($ticks - %start) ticks
}
My results (running each alias 3times):
nonsilenced 1687 ticks
nonsilenced 1703 ticks
nonsilenced 1703 ticks
silenced 1703 ticks
silenced 1703 ticks
silenced 1688 ticks