Ice Barrage: Shatter or pierce?

Ice Barrage QOL is miserable against trash, so for that, which is better?

Sublimation + Brittle Fragments:
60-90% more damage on Barrage sounds nice, but the minus 26-39% fire rate counteracts it a LITTLE bit (not a whole lot because Barrage has tons of fire rate else where). But what I’m really looking at is the -30% to the icicle delay. What really does that mean? In my head, I’m treating it as a separate -30% fire rate multiplier, but I don’t really know exactly.

Comparatively, 3 points gets me 100% pierce. I can’t tell if Sublimation is an increase or a decrease in DPS, generally speaking.