I don't have any graphs or benchmarks to post here, but can give my own experience. I pretty much exclusively play BF3. I run a Phenom II X6 1090t overclocked to 3.8GHz and an EVGA 460 2win(essentially SLI'd GTX 460 1GB cards). If I play on a 32 person or lower server I am *usually* gpu bottlenecked(not always, but almost always). Any higher player count than that and I am certainly cpu bottlenecked. I can turn my resolution to 800x640 or whatever the lowest bf3 allows is, turn all the graphics settings to low(at that resolution it almost looks like Goldeneye on the n64 lol), and my frame rate does not change. I am usually at around 40fps. It's playable, but I intentionally usually avoid 64 person servers because of it.
Interestingly enough, despite how much I hear 'multiplayer bf3 likes threads', I do not see much of a difference in min, max or average fps between having my affinity set to use all 6 threads, or setting it to only use 4. The main difference I see is that with 4 threads, all are around 100%, where with 6 none run that close to 100%. In my experience(which is very specifically my experience, could be the maps I play, some other bottleneck, etc. etc.) it doesn't usually utilize more than 4 threads. Also, this may be a difference because all my cores are physical cores and not hyperthreading. Regardless, I would benefit more from a CPU upgrade than a GPU upgrade at this point for multiplayer BF3. I would suggest the same to you if trying to play on 64 player servers. For me the decision on what to do is a bit tougher because I primarily use my machine for highly multithreaded work that the Phenom X6 does pretty good on, and gaming is a second priority. Maybe I'll pick up a Piledriver to hold me off until Haswell or Haswell-E.
Also, I intentionally run on US servers that I have a low ping to, and have 50/5 cable service, so I don't think my connection to the multiplayer servers is what's responsible for what I've seen.