Interesting discussion with one of the KiCad developers:
A few things stand out:
- keeping KiCad fast, even with large designs, is a priority
- Jon feels the rules based DRC is more flexible and potentially more powerful than mechanisms in existing PCB design tools
- they are working on a new Python API that will make KiCad easier to extend
- have implemented some new visualization features that make it easier to turn on/off various things and save these views to make it easier to route busy boards
We’ve been using KiCad 5.99 (v6 pre-release) on a project since the beginning of the year, and it has been working great.