http://bugs.winehq.org/show_bug.cgi?id=30154
--- Comment #7 from Dmitry Timoshkov dmitry@baikal.ru 2012-03-15 06:57:39 CDT --- Wine doesn't use command line xrandr tool, Wine uses xrandr APIs directly. Wine queries xrandr once at start up to enumerate available video modes, so it can return the data to the apps which query them. Also Wine calls xrandr API to change the display mode on behalf of an application request.
If a simple video modes query makes your X block for several seconds that's clearly a bug in your video drivers.