When the "Jenkins BuildContext Capture Plug-in" is activated, we notice that the loading of a "configure" page for a job takes more time each time the page is loaded.
When you check "Capture build context information" on your job configuration page (cf Screenshot), you notice that some choices on the combobox are duplicated many times.
The duplicated choices are : "Environement Variables" and "Job infrastructure files". The other choices are fine.

Each time you refresh the page, the number of choices is multiplied by 2.
We used firebug to see how many were generated, and we got a list of 7500, 15000, 30000 choices.