On average, response times and availability of five major social networks (Facebook, LinkedIn, YouTube, Twitter, and MySpace) has improved this past quarter, according to Web analytics company AlertSite. This is great news given that all of them (save for possibly MySpace) have a quickly growing number of users.

Despite a few outages, however, Facebook is still the fastest social network in terms of average response time. In the most recent third quarter (July 1 to September 30), Facebook shaved 0.02 seconds off its second quarter average response time, down to 1.00 seconds. Twitter and Myspace came in the last two spots with average response times of 2.93 seconds and 3.61 seconds, respectively. That being said, Twitter's performance improved the most over the last quarter among the social networks studied: more than 35 percent.

Speed isn't everything though: reliability is just as, if not more, important. LinkedIn took the top spot in terms of availability with 99.96 percent during the past quarter. Facebook and Twitter had the most downtime with availability rates of 99.76 percent and 99.74 percent, respectively.