Show timings in milliseconds

It makes more sense to show the timings in milliseconds than in seconds.
Examples (taken from the images in the README):

* 0.00200009346008 -> 2 ms.
* 0.0 -> 0 ms.
* 0.000999927520752 -> 1 ms.

Timings won't matter if they're below 1 ms anyway. If you still want to keep them you might want to make them clearer.