GPU H.264 decoding is pretty useless, especially for anime releases, due to its (retarded) limitations. It's a better idea to get a new processor (any dual core should be enough for decoding 720p anime releases with CoreAVC) if you're going to go the hardware upgrade route.>>13323079
What processor do you have? You could try turning off deblocking in CoreAVC options. It will reduce image quality though, but it makes decoding a lot faster.