In version 1.482 the feature "Report root causes of UpstreamCause in log and status pages" has been added. In certain scenarios (as stated below) this is absolutely not feasible because the amount of data logged per build might become dozens of megabytes. The result is that the jobs folder grows for several thousand builds in tens of gigabytes (within a couple of hours) which lets Jenkins hit memory limits and become unusable.
Some more words on the scenario which shows that problem. We have a Jenkins instance with 30 executors, and about 5000 jobs. I think the specific thing is that these jobs are not independent (or slightly connected) but have a lot of up/downstream relationships. The problem is that when Jenkins hits one of the leaf jobs the list of hierarchic causes which triggered that job is tens of megabytes long (I am not attaching a full log I guess the content is pretty obvious). On the one hand because the nesting level is very high and on the other hand since there are several paths through the dependency graph.
So there is an urgent need to optionally disable that feature. It basically makes Jenkins unusable in such scenarios.