There should already be quite strict limits on the number of forms and fields we look at but perhaps there are some edge cases we’re not handling well. We can’t really do anything about this without some clear instructions on how to reproduce the issue on a machine with development tools installed… unless you are a developer yourself and would like to investigate and propose a solution?
This might relate to the recent issue that someone was having with some particular configuration of 4chan: Experiencing severe Kee related slowdown on website