The more awesome Blender gets, the more jealous I am that it's not designed for CAD.

You may be interested in this: https://blenderartists.org/t/geometry-sketcher-constraint-so...

Someone implemented sketching in blender using the geometric constraint solver borrowed from Solvespace. It is also notable that the same solver has been used in FreeCADs assembly 3 workbench.

For the next Solvespace (3.1) release we have replaced the homegrown matrix operations in the solver with Eigen. In some sketches this seems be running 8-10x faster.