is cast with range indicators just as fast as smartcast?

I believe that quick cast without indicators will cast the spell on key press. If you do quick cast with range indicators turned on, it casts the spell on key release. The range indicator will show on the screen as long as you have the key pressed down, and you can right-click to cancel the cast.

Ive played both ways for a long time each. I think with indicators is just a hair slower. Not anything super noticeable that will hinder your gameplay tho