With that turned on, simply clicking to open and moving the mouse around in the Start menu drove the CPU to 90+% utilization.
I suspect this has more to do with specific hardware than it does with operating system. I have had expierence with two Dell Inspiron 8000's identical in every aspect except OS. The video hardware in these laptops is/was ATI's Mobility Radeon M4 w/32MB of VRAM. Mine runs Win2k, my friends ran WinXP Pro. Both machines exhibited substantial CPU load (80-90%) with menu drop shadows enabled.
When Phil's machine kicked the bit-bucket, Dell replaced it with an Inspiron 8200. This machine runs WinXP Pro and has nVidia's GeForce 4 Go video hardware instead of ATI. It doesn't flinch a bit with the drop shadows.
However, I installed the Catalyst 3.8 drivers on my laptop recently and I have yet to determine if the CPU load has improved.
