Finish leveling with lvl 40 warlock or reroll, what's faster?

Hey fellas,

I started my season with a warlock with which I have finished the new campaign and I'm around lvl 40 currently. Because of my health I currently don't have unlimited time to play but I actually want to reroll to a ww barb to play the lategame with it.

I'm looking for a way to quickly get into late game with a fresh barb. Would it make more sense to finish lvl 70 with the warlock because of any mechanic to level alts or should I just reroll to barb and start with level 1?

Any help on this topic is highly appreciated, thank you!