Mac OS X version 10.14 came with a lot of improvements - one of which was the additional tooling to the screenshot app.

A default feature of this new tooling was displaying a small thumbnail for a few seconds in the lower right corner. The problem is that the system waits 5 seconds before the file is created.

If you take a lot of screenshots the 5 second delay feels like an age. Luckily you can disable it.