I tend to have lot of windows: between 50 and 100 windows spreads over 9 virtual desktops. My taskbar only show the windows from the current virtual desktop (I don't understand why this is not the default yet).

Switching from desktop to desktop is very fast, but in KDE 4.1, the taskbar take several seconds to update the windows. This is not acceptable for my use. This blog will explain how I did to make it fast and use this as an example/tutorial on how to profile with valgrind/callgrind so KDE developers can keep their applications fast...