Hi @kouji, ahh ok yes there will always be that lag using that particular workaround, so indeed I am afraid you will need to wait for something as fast.
Another possible solution you might use is using a mouse recording macro which will simulate a mouse action, such as right clicking icon, then navigating to turn off/on eye tracker and binding this to a shortcut key. Would only work if the system tray icon is always in the same location, but worth a shot.