Really interesting point. I always figured I'd go with an ECS system like specs for the high perf case, but you're absolutely right, columnar storage is gonna be orders of magnitude faster. (Fun fact, the hibitset of specs looks _a lot_ like a worst case optimal join.) A GPU/FPGA accelerated Mech would be really really cool :D.

A hybrid system is a really interesting idea. I actually wrote my bachelors thesis on a system heavily inspired by EVE to be used for knowledge representation in robotics and have been experimenting a lot with implementations of the idea over the years. You should really open a Mech discord channel, I'd love to hang around and help build something like that :D.