I find that WEDs 3D view is fairly slow with heavy scenes. In other editors, such as Unity's, a heavy scene renders quickly, allowing the developer to move through the scene in real time, even at virtually full screen. In WED it is much slower, even on a high end PC.

WED's 3D view also needs a better quality real-time display. In today's world, the real-time display should be very near to what you see in the compiled game.