If you can't fix 9.0 lag then try this........
Since 9.0 like many I experienced horrible lag on my older computer. Lag so bad that I rage quit last week-end but didn't uninstall. I waited for the micro patch last week but it didn't help much. Everything is top knotch on my computer except for the old 8800 GTX video card which should run the game fine at low settings as it did pre 9.0.
Yesterday I stumbled across a thread here where it was suggested a player with bad lag install "WoT Tweaker" to ease pressure on his computer. Basically WoT Tweaker turns off, smoke, fires, explosion effects and other 9.0 features that cause older computers to lag. I had nothing to lose so with some help from here on the forums was able to install the mod successfully.
WOW!!!!! What a difference it made.
My ping went from 130ish to the 80 range and fps went from 6ish to around 20
Here are the links on the EU forums to the download. http://forum.worldoftanks.eu/index.php?/topic/125384-wot-tweaker-upd-for-090/#topmost
Instructions for Downloading and installing from "Deposit Files".
1.Go to Deposit Files via link on EU forums
2. Wait 60 seconds for countdown and enter the capcha in the box.
3. Download the .rar files
4. Extract the .rar files to you mail WoT folder
5. Go to the main WoT folder and Run WoT Res Unpack routine and click the make changes button
6. Now run the "WoT Tweaker" macro and choose which effect you want to disable.
7. Rerun the WoT Res Unpack again and click the new button that appears and you should be good to go.
8. Restart your game client
The author has a Youtube video showing and describing how to install the mod. He used an annoying text box to type instructions in Russain but also shows via screen shots how to install. Just skip the text and watch the installation steps and you will be fine. For some reason I had to do it twice for it to save so be warned.
http://www.youtube.com/watch?v=mQ9wwhpbsHI
Good Luck and I hope to see you on the battlefield. :)
Ober