Memory leaks are caused by not properly deallocating all memory for an object once its nolonger used..
In this case, memory is never deallocated from the wrecks in the main menu even though they are nolonger 'in-use', and the large number of wrecks is probably forcing state updates on each one every tick, bogging performance down further.
This generally is not an issue as just leaving the game running in the main menu on a decently powerful computer for a few hours wont cause any issues, but on a low end computer (like a cheap netbook) it can get pretty bad after a while.
It was enough to cause stuttering and lag on a 4GB AMD E350 HTPC we have after ~6 Hours (Possibly less since we just left the game in the menu while sleeping, woke up to see it was lagging. It would probably kill a 1-2GB intel Atom netbook outright, but we dont have one to test that on.
(Is this easy for the end user to fix? Yes, just restart the game or enter a game and exit it. But it was noticeable, and hence it got a 'trivial' bug level, but it honestly merits nothing more than that at this point imo.)
(This is probably a much bigger issue for the screensaver)
