I measured the scanning speed of the Sony a7S silent (fully electronic) shutter in this post. The answer was about 1/30 of a second. Someone asked me how fast the electronic shutter scanned in APS-C mode.
Here’s the scope shot:
And here it is with a white line superimposed so that it’s easier to figure out how many divisions it takes the shutter to go from the top of the image to the bottom:
The answer is a little less than 20 milliseconds, or 1/50 of a second.