Catching Up Speed

On further inspection, I noticed that 1 CPU core was maxing out at 100%, while the other 5 were much lower (10-15% range). Perhaps this is the bottleneck?

I suppose I might as well throw in an extra question: will avoiding graphic input lead to a faster catch-up? When catching up I usually zoom into a tiny corner of the map in the hopes of that it will make it go faster.

Catching up is limited by the speed at which you can simulate the game. I recently looked at some replays in Starcraft 2 and noticed that it essentially does the same type of catchup for replay seeking - with two big differences:

• It is easier to simulate Starcraft, there is simply less going on.
• The world is not drawn when seeking a position in the replay.

Disabling all the drawing in spring and in lua during catch up would make it a lot faster. This could be a nice PR for the engine. It would have to be an option because sometimes it is nice to get a quick overview of a game when you rejoin it as a spectator.

quote: when it comes to multithreading

your machine is a complicated system and operate at speed of its slowest element;
But if we oversimplify things there is a bottleneck which is RAM speed - CPU operates on its own pace, it need memory access to at least fetch instructions (also read and eventually write data); yes it requires multiple cycles to complete one instruction, but it typically does multiple ones in parallel if possible; and with multiple CPU cores at work (operating in their own memory regions actually) RAM can be simply too slow. If you want for example make animated loading screen in a game (smooth and independent of % loaded) then you can do this with multithreading without even thinking about it, but it another story when it comes to solve memory heavy task like simulating game of ZK.
Or at least i think this can be one reason why multithreading not so successfully implemented in games in general.