A voidsecond is the smallest measurement of time possible. A voidsecond is roughly equivalent to a reciprocal of Cantor's Absolute Infinity of a finite unit of time. This is the smallest measurement of time because of Absolute Infinity being a factor in the time here. A singular voidsecond is how long it takes for The Multi Omega to double their size.
This unit of time is too short to be useful in practically any situation anywhere, except for very rare individual cases. Even then, based on what your definition of "smallest" and "measurement" and "possible", is, the "Voidsecond" is only one of many others similar to it.