This Post is specially for opera lovers, Though i am not opera lover, but I believe opera is one of the fastest browser in this web world. Just follow the simple steps to speed up your opera Desktop Browser :

1. Open your Opera, Hit Tools menu -> Preferences -> Advanced -> Network.

2. Select Server name configuration.

3. Uncheck the following options :

Try name completion

Look For local network machine

Hit OK, and Restart your Browser.
Surely speed varies.