The network graph fails to render at all most of the time I want it. I suspect it's heavily cached, takes a long time to initially compute, and I'm only looking at graphs to see if a seemingly-abandoned project got forked and picked up elsewhere - which means I'm never seeing the cached version.

It also is (or used to be) possible for a particular graph to get into a wedged state; github support can fix that if you report the repo, but it's often not worth the effort for me.