With the Opera Browser the connection to the server can be made not only via plain old HTTP but also using the new, faster SPDY protocol. For this to happen, though, both the client and the server need to support SPDY. Unfortunately, it is not immediately obvious which servers do support such connections and which don't without analyzing the network traffic.
To make things easy on the curious the SPDY Indicator extension was created. It will display a blue thunderbolt whenever the currently selected tab has been loaded using SPDY.
- This extension will access your tabs and browsing activity.