run regedit
HKEY_CURRENT_USER\Control Panel\Mouse
Change MouseHoverWidth and MouseHoverHeight from default 4 to some smaller value 1-3
This will make the mouse cursor feel a lot more free from all the buttons that surround it.
In game you can adjust ui_SelectTolerance and ui_CommandClickScale if the cursor is not effective enough at selecting units and moving orders around.
Use console++ to set these everytime you play http://s000.tinyupload.com/index.php?fi ... 6625187226
This has a huge impact on cursor lag for me, would be curious to hear from others, whether it has any impact.