Not sure if it's a bug specifically, but I've noticed a number of times while viewing the site that one or more of my CPUs is maxed out and Firefox appeared to be the primary culprit. I've also noticed images taking quite a while to finish loading, which even with a few dozen images for a given IC/GB thread shouldn't take more than a second or two with my 100GB connection. Most recently, I only had geekhack and two other already loaded pages open, so I can't imagine it was a load issue. I haven't seen this happen with any other site.
Is there anything to the way the site is coded that would cause this or possibly something else unique about how GH interacts with FF?