Retri struggling with soloing content compared to Boomie

Hello,

I just did some tier 8 delves with both retri and boomie, same ilvl (prepatch).

With retri it took me more than double the time to clear it, while with boomie I was zooming through, kiting easily and deleting mobs around.

I thought retri would be much stronger in solo content compared to boomie.

Now I am back to being undecisive between pala and druid.

Am I doing something wrong? Any suggestions?