Safari 6 “Debug” menu: explain choices? There are certain menu items in the Safari 6 Debug menu which I want to understand.  

First, I’ll list the menu items; then, the information I would like to know for each of the items; and finally, I’ll post screenshots of the Debug menu and its submenus for context.



Specific menu items I’m interested in:


Use Buffered Windows
Use Single-process Windows
All items under Drawing/Compositing Flags ►
All items under Miscellaneous Flags ►




Wanted Information


what the menu item does
use cases where it would help performance
use cases where it would hinder performance
use cases where performance would probably not be affected




Screenshots of the Debug Menu

Screenshots from Safari 6.


Debug:
(submenu) Drawing/Compositing Flags ►:
(submenu) Miscellaneous Flags ►:
Use Buffered Windows :  
for each window, there will be another window that is off screen. The reason for this is that when the window the user is interacting with needs updating (ie, you move the mouse over the window) the WindowServer simply needs to copy the damaged region from the offscreen window and blast it over to the visible one. Similarly when the content of your window changes, applications are only supposed to update the region that changed. This drawing is performed on the buffer, which then is copied over to the 'visible' window. 
Use Single-process Windows:


puts all open tabs inside a single safari proccess instead of several ones.