Did you take a look a matrix~ in zexy yet? I often use matrix~ for dealing with volumes in greater numbers of sound paths. It has interpolation built in, but I never benchmarked it. I do however have the strong "feeling" that it is faster than using a lot of [line~]s or maybe even [line]s.
well, matrix~ is not using any loop unrolling / vectorizing features ... if i've got a simple volume control, it's more or less a vector/scalar multiplication, sometimes this scalar will change ... so a |*~ 0| would perform best ... is suppose matrix~ will add some overhead (no benchmark, though)
cheers... tim