Clean up usage of Linq and `.ToArray()`.

Both Linq and ToArray produce allot of Garbage, and should not be used at all unless absolutely necessary. Using it for loading and saving is ok, but in a game loop no. This is because things like ToArray make copies of the data. If these are only used for a short period of time then the garbage collector will need to clean them up. It would be better to use the lists directly. Also .Any() should be removed in favour of .Length > 0 for exactly the same reason.

We should review all the code and remove usage.