You can see what automation tasks are in the queue from psql (or rails db):
select id,priority,method_name,state,queue_name,class_name,zone,role,msg_timeout from miq_queue where class_name like '%Automation%' or class_name like '%MiqAe%';
Anything with a state of 'ready' is waiting to be dequeued; anything with a state of 'dequeue' is currently being processed.
The automation engine is serviced by a generic worker, and each worker can only handle one job at a time, before looking to dequeue the next message. It may be that you're already running two automate tasks, and have the default of 2 generic workers. It might be worth increasing the number of generic workers on your appliance(s) and seeing if this shortens the delay (this is done from Configuration -> select server -> Workers in the right pane)
Hope this helps,