From my point of view,
JENKINS-13547 is not fixed - but I did not dare to reopen it. :-|
Using tcpdump we measure several thousand requests per minute from Jenkins to our Crowd server - though there is no significant user traffic on Jenkins.
When trying to increase the "Session validation interval" parameter of the crowd2 plugin configuration, it always is reset to "2" after saving and reopening the screen "Configure Global Security".
Also, the parameter does not seem to have any impact on the number of requests sent from Jenkins to our Crowd server.