I was just playing a ~4 hour long game, a 4 way FFA with hard computers. After about three hours, I noticed that I couldn't see the weapons fire from some of my ships, so I tried the save/reload trick to fix it. It did fix it, but more than that, it brought my framerate up from like 15 to 60.

Why did it help my framerate so much, when all the same ships should've been in play? Does the game have memory leaks? Does loading a save secretly change your settings to low? When I saved/loaded, a couple players had been wiped out since the start of the game, so maybe that freed up some texture memory that wasn't being used anymore but hadn't been released, or something.

Anyway, for those long games, consider saving and reloading every couple hours. It might run a lot better for you too.