I am running 4 mongrels behind nginx with two servers blocks (one ssl enabled). I have a public facing app that 20-30 users go through each day (non ssl) and administrative SSL controllers in the app that people at my office use. I am noticing that by the end of day after a lot of use of the SSL version of the app, that some requests are hanging for certain people in the office (Mac OSX and Windows Firefox 2.0.0.5-10). It very rarely hangs on my machine (Linux), but it happens every now and then. I don't think the mongrels are dying because usually when these people encounter the hangs we can go to other computers (Linux Windows OSX) in the office and hammer on the SSL portion of site with no problems. Also, the non SSL version of the site never has any hanging AFAIK.

One thing I did happen to notice as well, is if I do performance testing on SSL with httperf, at first it is decently fast, but on many sequential runs it consistently degrades until httperf can barely do any requests. However, even while I do an httperf I can use the SSL version of the site with different computers. It just hangs on some, usually towards the end of the day.