Originally Posted by Zonx
It's possible (not confirmed) that there is a performance bug on live that is magnified by v11 changes to the Maintained and Refresh windows. I personally have not noticed any significant problems, even while 2-boxing on the same machine, which leads me to suspect it may be specific to certain hardware.
I took my newly low-frame-rate fetish system, and just deleted eq2ui_mainhud_maintained.xml and _Fetish_refresh.xml as a quick test. Framerates in Antonica jumped from 15fps to 99fps (Default gui runs 105fps, close enough). Guild hall jumped from <5 to >15. Using a prior version of maintained.xml fixes the problem as well. I just left refresh removed.
Both the maintained window and the refresh window appear to be separately guilty. With neither, 15fps. With either, 25-40 fps. With neither, 99+fps.
Edit: (All numbers for Extreme Performance. Other settings are similarly affected, only Extreme Performance was remotely playable)
Hope this helps.