Sin dorei

From EJ forums:

Originally Posted by Masnie
Does anyone have any experience with Leatrix Latency Fix : WoW Tools & Utilities : WoWInterface AddOns? Since I moved I don't really have the best connection and a housemate claims that this dropped his ping tremendously. Then again I'm not sure if it actually improves network speed, or if this just shows better ping numbers and makes you feel warm and cozy.

This is simply the standard registry change for Windows in a userfriendly package. It changes characteristics in how your Windows is communicating using TCP connections and is more suited for WoW's usage pattern. It does help, if you haven't done this already and should lower your latency. Wheter it is noticeable is another issue though. It can and will not fix a crappy connection with packet loss or problems within your provider, but it is a simple reversible change that normally does not impact other traffic (websurfing et al.) while improving your latency a bit.

I described this registry hack at the start of WotlK in my (otherwise probably pretty outdated) blog entry http://elitistjerks.com/blogs/cadfael/ under section 2 (how to apply it manually), it's the same thing.