Window compositing needs more work (everything doesn't show up at the same time) ...

Sometimes, in XFCE, when opening an application, the application window doesn't appear at the same time. Sometimes, the window border appears first, then the body of the application shows up a second or two later. This happens with Firefox, etc. Most prominent is Okular when there's recent items listed in the opening screen. Would appreciate more consistent window performance across the board. Thanks.