Here's a nice little tip to make the game start faster. A friend of mine sent me this info.

Create shortcut for the game (a .bat file should work too). ACBMP.exe is for multiplayer and ACBSP.exe is for singleplayer. Right click on the shortcut and choose properties and then add these respective parameters to the "target" box:
Singleplayer parameters: /launchedfromotherexec /username:YourUsernameHere /password:YourPasswordHere
Multiplayer parameters: /launchedfromotherexec /onlineUser:YourUsernameHere /onlinePassword:YourPasswordHere

As an example here's how the target box would look like:
"C:\Program Files\Ubisoft\Assassin's Creed Brotherhood\ACBMP.exe" /launchedfromotherexe /onlineUser:MrBob /onlinePassword:BobBob1

That will start multiplayer instantly with the login info MrBoB/BobBob1. And yes, you do have to write your password in the shortcut. If this is a computer which other people has access to, this might be a bad idea as they'll see your password if they check out the shortcut.

Another thing to note. I'm not sure what would happen if you do this with an outdated version of the game. I dunno if it'd properly see if it's the wrong version and then quit and update, or let you proceed with the wrong version. So make sure your game is up to date when using these shortcuts.