In Windows it is a bit odd anyway, as anything drawn using GDI or GDI+ goes through the CPU. This includes the "classic" interface. For accelerated interfaces (

In Windows it is a bit odd anyway, as anything drawn using GDI or GDI+ goes through the CPU. This includes the "classic" interface. For accelerated interfaces (Aero), the GPU is involved (but don't ask me how - perhaps someone could elaborate?), so on rubbish GPUs it may be slower than going through the CPU, perhaps? Windows should tell you that your computer is rubbish so won't attempt to use the Aero interface. If you elect to not use the Aero interface, it'll then attempt to mimic the Aero interface entirely in software using GDI+. This is indeed far slower, as the command to draw a series of lines and bevels obviously means more CPU calls than a single "draw grey rectangle" command. The interface is not drawn using precached bitmaps, but is done by software commands. More complicated drawing = more CPU = slower Windows gives the option to turn off effects like shadows and transparency, window contents whilst dragging etc. in "performance" options in Control Panel, as these would mean more CPU calls (there's more drawing going on). If it wasn't faster, why would it be under "performance"? But as you state, to a human perceptible degree it may not be noticed. I find that opening Windows Explorer on Windows XP is a far faster drawing experience than opening it on Windows 7, where it needs to fade into view and then redraw the tree on the left, the pane on the right, the toolbar with gradients (gradients are not free!), the "places" tree above the tree on the left (how confusing), and the giant blue panel that sits at the bottom to draw a picture of a computer in addition to the status bar. File Manager on Windows 3.1 was really fast by comparison. EDIT: Actually, on OSX I am left with "whitewashed concrete grey" with "primary pre-school colour" red orange and green. Full circle really!