I have been working with the US team to find the lag issues in the client but until things are fixed I made a patch that will fix the client lag in Auto IT
The download and source code are at this location
Downloads - requiem-lag - Requeim Lag Patch - Google Project Hosting
Where it is made in Auto IT some Antivirus applications will flag it as Gen:Trojan.Heur.AutoIT.4
Virus Total Report is here
If you do not trust it then you can download the source and build it your self
What I did to find the lag was watch the process with process monitor and see what i/o reads the client was requesting that it was looking for in the root of the install directory.
What I did to fix it was place the files that it was looking for in the root or in folders to stop the loop of it looking for the files.
You should see a reduction of lag in FOC,SVS,TB,most towns and the lag from skills will be gone
This is tested and stable in the US client but it should work with the SEA client as well
Enjoy install instructions are on the google code site and I update it if they mess something up in the updates