This was a massive overhaul and that’s why it wasn’t possible to make this update in weekly increment - so thanks a lot for your patience!
We had to redo major parts of the engine and there was a lot of experimentation - for example changing the prediction protocol on client-server and observing if it’s better for user experience or worse, and many more. Space Engineers has many systems and special care had to be taken for each of them: player character, jetpack, ship, wheeled vehicles, voxels and planets, fast moving objects, deformable entities, antennas, player standing on a moving grid, colliding grids, rotors, pistons, wheels, and many many more.
But wait - that's not all! With this massive multiplayer update we are releasing optimizations and performance improvements, Safe Zones, Female Engineer and much more!
Full list of features and improvements: Forum.keenswh.com
Marek's blog post: Blog.marekrosa.org