This reminds me of Mischief (for Mac and PC) [1], which is incredibly fast vector drawing application.

The way Mischief handles its details of graphics, speed and huge range of zoom is by using adaptively sampled distance fields (patented technology) [2].

It would be nice to know if Affinity Designer uses some advanced technology to achieve similar properties.

[1] http://www.madewithmischief.com [2] http://www.cs.tufts.edu/~frisken/frisken.html