From what I can read in this recent post in the Tor blog, Hidden Services use one single guard, just as regular clients do. How does this affect the performance of hidden services? I know that since the single-guard proposal was implemented, the conditions on bandwidth that a node has to satisfy for becoming a guard are much stricter than before. However, for hidden services such as Facebook's, it seems that despite the load-balancing at the web server, the guard could become the bottleneck. Is there any analysis done on this?