Everyone has their own standards.
Agreed. My point was: comparing these different standards is hard, if you don't use exact numbers. And that is what most people seem to do: do a lot of handwaving. Not only in this thread, but in general, imho.
My fiancee is really happy playing on the athlon ii x2 250 + 9600 GT rig I built for her. She gets 30-60 FPS at Good settings at 1366x768. My friend absolutely couldn't stand his FPS dropping below 60 on Ultra, and hence we built the i5 2500k + 5850 rig
I bet your fiancee doesn't do raiding ? Maybe your friend does do raiding ?
Your fiancee runs at 1366x768, your friend might have 1920x1200 ? That's 1m vs 2.3m pixels.
Your fiancee might not use AA, your friend maybe wants 8xAA ?
Good settings versus ultra settings makes a big difference in itself.
So my point again: you can't compare numbers people give you. Unless you know exactly what those numbers stand for.
OP sounds like he wants to get a constant 60 fps too, and 2500k overclocked is the best route for that right now. The video card he has should enable constant 60 fps at 1080p with lowering only a couple key settings
And who says that replacing his CPU will have the biggest impact ? I think that "lowering only a couple key settings" will have a much higher impact on fps. At zero cost.
Look at Tom's Hardware. How did he do his testing ?
http://www.tomshardware.com/reviews/world-of-warcraft-cataclysm-directx-11-performance,2793-2.html
He took a flightpath through Twilights Highlands. Outdoor areas only. And when flying, you will see some players and NPCs on the ground, but not many. Result: a benchmark that is a lot less demanding than being in a city, or doing 10/25-man raiding.
Now let's look at what numbers Tom is getting:
http://www.tomshardware.com/reviews/world-of-warcraft-cataclysm-directx-11-performance,2793-5.html
Ultra settings. 1920x1080. Using a i7-980x (I think).
gtx580 - 103fps.
gtx460 - 81 fps.
Remember, that is average fps in a simple outdoor flight ! If you go raiding, or to a city, you can expect half of that framerate. And the lower boundary will drop even lower. My conclusion is: it looks like the OP's system is performing in WoW as expected.
Now the second question: will upgrading to a i5-2500k help his framerates ? I'm sure it will. But how much ? Look at these 2 pages:
http://www.tomshardware.com/reviews/world-of-warcraft-cataclysm-directx-11-performance,2793-9.html
http://www.tomshardware.com/reviews/world-of-warcraft-cataclysm-directx-11-performance,2793-10.html
Tom's conclusion: "Clearly, AMD's CPUs are holding back performance in Cataclysm compared to Intel's processors."
But there are 3 factors here that should not be forgotten.
1) Tom tested at 1680x1050. When playing at 1920x1200, the impact of the GPU increases, and the CPU decreases. If the OP plays at 1920x1200, upgrading his CPU will have less effect on his framerates.
2) Tom doesn't say which GPU he used to test the CPUs. But he should have used his fastest GPU, to make sure he tests CPU-performance, not GPU-performance. So I expect a gtx580 was used in these 2 particular tests. Gtx580 gives higher absolute framerates. But the OP has only a gtx460. When replacing the CPU, the absolute change in frame will be lower too, than in Tom's tests.
3) The problem is when raiding. One of the problems there is that during raiding, there are a lot more spell-effects on the screen. I would guess that spell-effects are mainly a load on the GPU, less on the CPU. This is different from performance in cities, where fps are more impact by the amount and constant change of players and NPCs on the screen. So in raids, I would expect the GPU to have a large role on low fps than it would have in situations like the benchmark (taking a flightpath).
This is all speculation. I don't play WoW anymore, so I can't test anything myself. And as we know, testing in WoW has always been very limited because you can't redo test-runs reliably. But it is my belief that upgrading the OP's CPU to a i5-2500k will not suddenly improve is average fps in raids from 30 to 60.
As I've written in an earlier post. If you can sell your current cpu+mobo+ram, then go for it, buy a i5-2500k and see if WoW runs faster. But if you have to pay the full price for a new cpu+mobo+ram, I doubt that the 300-400 euros is worth it. Personally I would 1) turn down shadows a notch, and 2) wait 6 months, and buy an Ivy Bridge. I know the pain, I have a E8500 myself, and I don't find it worthwile to upgrade yet, because the games I play (e.g. Fallout3, Portal2, Witcher1, and even Crysis 2) do not benefit enough to make it worth the money. I'm waiting for IB.