Please let me know if any other info would be useful, I'm eager to assist getting this fixed however I can Thanks.

Need some information to understand why the call to https://foo.example/job/Branches/view/feature-box_polling/api/json takes that long. Threaddumps would be helpful during the call that timeouts.

@Patrik, here's a thread dump of master and slave (I believe slave was building a job at the moment), in another couple tabs I had the delivery pipeline view open and these GETs can be seen in the dump: https://dl.dropboxusercontent.com/u/2112716/Thread%20dump%20%5BJenkins%5D%20delivery%20pipeline%20timeout.html

I found the issue: I have a job called "Job-DSL" which is a pipeline step, it runs the Netflix Job DSL very frequently. I wasn't discarding old builds, so thousands piled up. Once I cleared the builds directory, the delivery pipeline started working (and snappily) again.

Marking as resolved since it seems to be caused by job configurations preserving a lot of history. A workaround is to preserve less history.