Turning off display compositing turns on window transparency after reboot

If I go into window manager tweaks and turn off display compositing, then reboot my system, then upon logging back in xfce will have transparency turned on for all window title bars and for all inactive windows. And, because compositing is turned off, I'll experience system lag and high CPU usage.

Near as I can tell, the only opacity settings for those things are in the display compositing, so they shouldn't be getting enabled.