Errmmm, last I checked this game uses as many cores as it can get. O_o Point me to the thread where it states two cores only. Because I see activity on my other four cores. Considering the PS3 has like...6 Logical cores, no?
Also, my GPU tops out at 73C....mayble you need better cooling in your case or turn up the GPU fan. Many recent games that bring a GPU to 100% usage cause the same heat.
As far as memory leaks go...why would you play for 4+ hours in one sitting. Hell, normal players won't even see such errors.