I have noticed that the requestDelay settings or the whole a4j:queue is not working after a page submit.
When I open the view the requestDelay works fine and 4 seconds after a keyup event in the input field, an ajax request is processed.
But when I press the commandButton the queue functionality is lost and ajax requests are performed immediately without a delay.
The same problem exists when I use <a4j:attachQueue>
I found out that this issue is related with PARTIAL_STATE_SAVING context parameter in the web.xml.
I need to disable this paramter otherwise some views won't work correctly.
If this paramter is enabled the a4j:queue works like it should.