I have a 1mm sphere and can't use zoom or scroll to navigate properly, to be clear, at first it was impossible to zoom in, then I change the view port scale to 0.001 and again to 1000, after that I was able to zoom in, but not too close of the object.
The other issue is with the scroll orbiting, when I hold Shift the movement is really slow and without Shift too fast, is really hard to control.
I have some objects in a normal size (about 10cm) and need to work with this to scale, when I changed the view port scale to 1mm I couldn't zoom out to use the bigger object.
I'm using Blender 2.81