When turning off power to a redstone lamp, there is a delay of a fraction of a second before the lamp actually goes dark.

This is most noticeable in clock circuits involving redstone lamps, which no longer work correctly.

The attached video demonstrates the issue. The piston in the video demonstrates that the clock circuit is indeed working correctly, however the redstone lamp does not turn off quickly enough to produce the expected flashing effect.

I'm also experiencing frequent crashes when I open a world and look at a clock circuit containing a redstone lamp like the one in the video.

Edit by SuperGeniusZeb: By using observers, you can clearly see that this behavior is in fact a functional delay, and not just a visual one. Hook up an observer to a redstone wire, and have that wire hooked up to a redstone lamp. Make another observer observe that lamp, and power the wire. Both observers will output a signal simultaneously. Now unpower the wire. Notice how the observer that is observing the redstone wire activates before the observer observing the lamp does.

Also, I can't repro the crash mentioned in the original description, so I assume that was a separate bug that has long since been fixed.