Assassin's Creed is an awesome game, but recently my install has been
driving me up the wall with stuttering every time I get into a fight
or kill someone.
This persisted across multiple OS installs and caused me to stop playing the game for a while. Finally I have a solution.
After spending some time investigating the problem, I realised that AC is calling home each time you kill someone, to a server at 216.98.48.18. A bit of Googling suggests that this is to collect statistics to help make AC2 a better game.
Some suggest that the server is down, which is causing the stuttering as the game waits for a response, however Wireshark does show a response, one can only hope that Ubisoft release a patch to fix this issue, but in the mean time, there is a another solution.
Assuming the IP address is the same, and you have Administrator rights to the computer, open C:\Windows\System32\Drivers\Etc\Hosts in Notepad, and add the line:
216.98.48.18 localhost
Save the file and re-load Assassin's Creed, the stuttering should now be gone as the game will try to connect to your own computer instead of Ubisoft's, fail and give up almost instantly.
If you do not have Administrator access to the machine, the only thing you can do is pull the network cable.
That's fine too, we just need to know what it is, and here's how.
What the output of netstat shows is the active sockets (connections) on your PC. As you can see above, there are 5 established connections and 3 that are waiting.
You want to look for a IP address that begins with 216.98, the last two digits may be different from what is above, and that should be the Ubisoft server.
Sigh! It's possible in some regions that the IP address is entirely different. If that's the case, to be absolutely sure, I recommend that you reboot your PC, before doing anything get Assassin's Creed to stutter and run the 'netstat' command, see above.
Hopefully you will now only have 1 IP address, if you have more, you'll have to enter them into DomainTools' WhoIs lookup database, this will tell you who owns that IP address block. You may be a little out of your depth here, but it's OK, you're looking for Ubisoft owning the IP block. :-)