Your CPU is only in SECOND place when it comes to deciding how a game runs. Graphics is the quality that is in consideration, and CPUs have Zero to do with game-capable GPUs' operations. If you have a low quality graphics solution, then you get the matching game settings, but Oblivion id nearly five tears old now, so wjat was Low End back then is now aboriginal!
Ignore my misuse of terms. What I mean is back then, on the same machine, I was running the game under Ultra High. Back then it also said it recommended me on low settings. Before my response was the game was having trouble reading my specs or something to that nature. My question was why I couldn't select ultra high etc. Figured it out, turns out I had to download the patch in order to get those settings. I'm running it on ultra high again and there's zero issues or lag. Problem solved. Sorry for the thread.