I'm looking for guidance on debugging slow page load times. Ever since we upgraded from 1.480 to 1.484 (and other versions beyond that) we've had very slow page load times. Sometimes upwards of 120 seconds to load a page, nearly any view tab, job configuration etc.
I've debugged many Java apps and I'm confounded. There are few, if any, Full GC's occuring, regular GC's occur somewhat frequently but take .02 or less seconds. CPU utilization for the java executeable is under %6 and and disk utilization is reasonable (we're averaging a %90+ idle time). The initial HTTP ack comes back immediately but then we wait for the page response to come back for up to 2 minutes sometimes. Othertimes it loads reasonably fast (under 4 seconds). When it's hanging, it's hanging for all requests, much like it was doing a full garbage collect. It feels like some kind of resource contention.
But I cannot find where the contention is, thread dumps look nominal (I've included one here for example). Something causes long page load times, we back revved to 1.484 thinking it had something to do with lazy loading features but clearly it does not. On 1.480 we did not have these issues. I could use some help figuring out what else to look at to identify why Jenkins is slow. There is a lack of information available on common reasons for slow page load times, this results in a terrible user experience with an otherwise fine tool.