New HDR task queuing - Why is it so slow?

First of - I am VERY grateful (as are hundreds or thousands of other real estate and hdr photographers) that we can now have at least some form of decent task queuing!

The question that arises now, is why are those tasks so slow now?

I used to be able to process a 5 shot HDR in roughly 20 seconds a piece when doing them one at a time... Now with the task queuing its taking upwards of a minute or 2 for each one in the queue to actually process.

Are the tasks in the queue supposed to run concurrently or one at a time?

Is there some new setting hidden somewhere to change that behavior?