Here’s a short video of a player who cleared Kurast Undercity on Torment 4 with their Sorcerer in just 1 minute and 16 seconds.
This build combines permanent 
Unstable Currents, high mobility, and auto-proccing spells to fill the screen with lightning spears and AoE damage. It works very well with mid-tier gear, and comes with solid survivability with 
Ice Armor, 
Flame Shield, and decent defensive aspects.
