Please have a look at the results of my standby battery consumption test:
http://xdaforums.com/showpost.php?p=20463009&postcount=525
I identified your kernel to be responsible for the high battery consumption problem (only when WLAN is activated). With stock kernel everything is fine.
I have a few questions before I can start to look into this. I need more information and need to understand how consistent your tests were run. Please be honest with your answers. If you are not sure, please say that you are not sure. I can dig for some of this info in different threads, but it is best to have your confirm it all here.
Do you have a 3G model?
What version of the kernel was used (assuming version 2d).
Were you overclocked? Did you use undervolting? Was it the same for every test case?
Did you have WLAN set in Android to shutoff when the screen goes off in every test case, or was it setup to leave it on? I believe there are 3 settings to choose from. Please confirm what setting you used and whether it was the same for every case.
Did the Android battery usage stats (under Settings|Applications) also suggest that WiFi was using more resources during this time for the suspect test cases, thus suggesting that WiFi is the problem? It would be nice to see screen prints of these stats along with the graphs Android provides.
Were you flashing fresh for every case and running the tests without installing any extra apps? Or perhaps you are restoring some of the test case environments from CWM backups where you may have had different apps installed after a previous configuration? What I am getting at is whether the same stock options exact same apps running (or not running) for every test case?
Did you activate the USB charging script on boot for every test, or was it not activated? Since this is a power related mod, it would be interesting to see if it plays any role.
After we get some additional info, we can also check with others to see what they are seeing as well and I can run some tests with my WiFi-only version.
I am getting about what is expected from stock on my Wifi only model, while taking OC into consideration and I never turn Wifi off, even with the screen. I also have an Iconia and the GT8.9 does much better on battery as you suspect. Both are OC'ed at 1.5GHz.