Blade Vortex and Cast Speed

Can someone help me re-word this?

Blade Vortex Wiki https://pathofexile.gamepedia.com/Blade_Vortex

"Blade Vortex's in-game tooltip DPS gives the average damage of one hit from one Blade Vortex instance, multiplied by casts per second. This value is misleading primarily because Blade Vortex can hit more than once over its duration, thus not cast speed must be used, but hits per second (rounds per second, spin rate), over the duration of the stacks."

The tooltip doesn't give me rounds per second, only damage per use and casts per second. So if I build cast speed does that mean it's only affecting how fast I can accumulate spinning blades? I did some experimenting, if I put a Faster Casting support in my chain I can build up 20 blades in 5 seconds. Without it, it takes 7 seconds. With a Spell Echo it takes 4 seconds.

Also, when I add the Faster Casting support my damage per use in the tooltip stays the same. When I add Spell Echo, it actually goes down. But the casts per second are affected accordingly. Does this mean Faster Casting does absolutely nothing for my damage once I reach 20 blades? And Spell Echo is only decreasing my damage?

Yes, cast speed only affects how quickly you can generate the blades, the hits per second is only dependent on how many blades are active.

So cast speed still helps with DPS, because you ramp up to a certain DPS value faster, and it makes it easier to maintain max blade count. Same thing for Spell Echo, with the added effect of the less damage multiplier.

Thanks dude

One more question. If my tooltip damage says 20,000 damage per use, how do I convert that to effective damage per second when I have 20 stacks? I checked Path of Building and it says I am doing 33,234 DPS. But it seems like I am doing a lot more than that. I don't really understand the Wiki on Blade Vortex where it shows all of the equations.