I wouldn't do anything untill a while after the full release hits. Give them time. Just know it will get better. Perhaps try and stick to 32 player servers for a bit as that's supposed to make things run smoother.
I have a Q6600 and a 5870, run everything on High and it's 40-60fps. I have tried dropping to medium but doesn't make a huge difference and the graphics look bad. Medium textures look horrid.
I don't think DDR3 is the answer to your issues. IMO it wouldn't make any difference at all to you and you'd be looking at a new Mobo, RAM and CPU
I've checked taskman while the game is running and all 4 cores on my q6600 are ~60% so it's by no means the bottleneck here.
Remember it's early days, TWI are working flat out but they can only do so much in 7 days. Just be patient and they will get there.