I've tried the workaround in the JIRA issue to add
a:attachQueue requestDelay="0" to the rich:tabPanel. This only works party. The tab panel works again but the request delay specified for the autocomplete is not used anymore.
The only advantage is that the ignoreDupResponses="true" from the queue for the autocomplete is used. So the user does not see changing suggestions anymore. But it would be nice if one could avoid the unnecessary ajax chatter with the server.
Update: At least it works as expected on all pages that doesn't use the rich:tabPanel with switchType="ajax". On the few pages where I use it the request are send without request delay.