Weird rumble scores

You are right. Apart from creating many thrads that do a lot of work when it’s others turn, creating a lot of objects to increase GC overhead does affect others’ bots as well, making the result a little bit random. 

But I doubt how much difference can GC overhead put. The most unreproducible scores I experienced are always coming from some rare exceptions, say 1/1000. And once happened, it causes some random pairing to be close to 0. If averaged with some normal score, it really looked like it’s decreasing with no reason. 

But there’s always some reason, and mostly coming from specific bot instead of the clients, since not everyone is affected.

So my advice is that you output exceptions to file, and check if there are any. Skipped turns could also be counted. I was doing this in older bots as well, and concluded that GC overhead & skipped turns aren’t really the problem, but exceptions are.