Half the time you try to cast something mid volley, it doesn't even register. When it does register, you cast a spell and then the attack animation restarts, giving you the very long initial attack animation delay. This doesn't really make sense, considering warlocks are supposed to blast/spell casting hybrids.
Solution: get rid of initial delay. Space out the blasts a bit more, so that the attack speed isn't too high. Do some things to make sure that spells actually register, otherwise it will be a really frustrating class to play.