Over the past week or so, I've noticed a significant slow down of the SE sites I frequent, namely, stackoverflow.com, superuser.com and russian.stackexchange.com. Most of the times, the load time for the site is in 30-40 seconds interval.
On further investigation, it seems that
cdn.sstatic.net is the culprit, specifically files
all.css that are loaded from that domain - it takes about 20 seconds for each of the files to load. Ping response from cdn.sstatic.net is fine (about 2-3 ms), therefore it must be something with the web server response. Sometimes everything is fine, but most of the times the load time makes the site all but unusable. Here's the screenshot from the firebug showing 18+ seconds load for each of the two files.
I get this behaviour both, from my work machine (linux ubuntu laptop, both firefox and chrome) sitting behind the corporate firewall, and my home machine (macbook pro, os x, both firefox and safari).
It's worth noting that the issues started manifesting themselves only about a week or so ago (maybe slightly more than a week).
I found this post about similar issues, dated 2 years ago, but I would hope this is not really an ongoing issue.
I'm accessing the sites from London, UK (work) and from Woking, UK (home).