I have a AMD A10-4655m APU with Radeon HD Graphics 2.00GHz Processor, 8 GB of RAM. 64-bit Operating System x64-based processor. And im using Razor Cortex. Can I run better cities?

You have a better computer than my ancient 2007-era steam-powered machine, and I run Better Cities pretty well. My only problem happens near the Waterfront District. But, then, I'm not a person who plays with one eye on the frame rate counter either. As long as a game feels fairly smooth to me, I'm happy.

so its sorta laggy? but not to much where the lag is unbearable ?

Everybody gets some lag in Oblivion in some places, depending on mods and graphic settings. It's a badly optimized game, and heavy mods, particularly those that add more AI load (NPC activity) tend to bog down the CPU.

That's been my experience. I've got a i-5 4670k CPU, 16 GB RAM, and a 3GB 780ti GPU and I get lag around the waterfront of all cities that have waterfronts. But once I went back to vanilla LOD, the lag nearly vanished. TES4LODGen makes the game look great, but was a real FPS killer in my heavily modded game.

Oddly enough, the area around Anvil's docks actually ran a lot better in my game with the open cities than when the cities were closed.

The Oblivion engine is just so poorly optimized it does not matter how great your hardware is, enough mods will slow it down.

"Unbearable" is subjective: it means different things to different people. That's kind of what I ws getting at when I said I don't play with one eye on the framerate counter. To other players, framerate is crucially important. There are players who put massive amounts of effort into making sure their framerate does not dip below 60. Myself, I don't much care. If the game doesn't draw itself to itself by stuttering, I forget about it. You might feel different. All I can say is, it's not unbearable to me.

I should mention that I don't use texture or mesh-enhancing graphics mods. I also don't use mods that extend the view distance (if fact, I mod most of my games to decrease my view distance). Most of the modded load my computer has to put up with comes in the form of added NPCs and some scripts.

And as glargg pointed out, even the game is going to stutter now and then, no matter what. Even without mods. I try to take it in stride when this happens to me. I usually roleplay that there is some kind of magical phenomena going on somewhere in this magical-infused world that is causing a temporary space-time hiccup, the nature of which my character does not understand.

Agreed. To me, "unbearable" lag in Oblivion is anything less than about 15 FPS where your game actually starts interfering with your ability to control your character to a significant degree and your game starts looking more like a slide show than a video.

For me for any game is getting stable frame rates and no screen tearing, especially no screen tearing. I do not mind a stutter here and there happens with a new cell load or if doing a save.