Comment by klibertp

PvE vs. AI on maps larger than 10x10 slows down to a crawl after ~40minutes. It's not FPS (which remains perfectly smooth), though: it's the simulation speed, influenced by pathfinding, trajectories of every single projectile, managing construction, managing units' scripted movement, and all the AI decision-making. Plus the performance penalty of using Lua (and its GC) for parts of game logic. Apparently, all of that is crammed into a single thread, and by the time you have 1k units, simulating 1 second of in-game time can take 3-4 seconds (or more, obviously, depending on the CPU; but single-core performance stopped improving drastically at some point). It's been a few years since I last checked, but I'd be surprised if anything beyond 20x20 maps would be playable against the AI, even today. And since it's a matter of codebase architecture, fixing it would require a rewrite (someone in this thread is actually attempting it, which could be fun).