My copy of C2C is only about a month or two old. Did you mean an update that is newer than that?
You may need to check the version number in-game (hover over your flag in the UI). If you got the game via Desura then you have a very old version, probably more than 10 versions old since Desura has never updated the version they install. If you did not get it that way then you are probably only 1 or 2 versions behind. Version 34 was released about a week ago. A relatively recent version, v33 from last September, added a new "graphics paging" system which should reduce memory usage by something like 30% compared to the version 32.
I did the 3gb switch too but it did nothing for me either. I believe a lot of the discussion in the past was about that, hence why I'm asking again. Sometimes the threads just need to be re-started to get a 2014+ answer.
I'm fairly certain that the 32bit limitation wouldn't affect memory too much, but I could be wrong there.
The 32-bit thing is the entire source of the memory problem. The best you can do is to run a 64-bit version of Windows which allows the program to use a full 4GB of memory (if you are using a 32-bit version of Windows it is pretty much useless to have more than 4GB installed in the computer).
Since you say you have a 64-bit version of Windows and 12GB of memory the rest of this is probably not relevant, but here you go anyway:
On a 32-bit version of Windows the program can never use more than 3GB, and only that much if you use the 3GB setting for the version of Windows you are running. Otherwise, using the default settings, the game can only use 2GB at most. If you use the "3GB" adjustment method for the wrong version of Windows it will do nothing useful. Even using the correct method may not be entirely helpful - I tried it a few times and it reduced the MAF issue but did not eliminate it, just delayed it, and it caused some other problems (although it was generally with other software - there was some stuff it couldn't load into the reduced system memory space that I occasionally needed). A 64-bit version of Windows does not have a "3GB" switch since it can already use way more than that (there are built in limits, but those are added in on purpose - I think the Home version of Windows 7 64-bit can use a maximum of 16 GB for the Premium level and "only" 8GB for the Basic level and the Pro version is much higher - something over 64GB but I am not sure exactly how much, although it doesn't matter since regular motherboards and chipsets don't support more than 32GB anyway).
On the other hand, there is a second memory problem: graphics card memory. If your graphics card does not have very much memory it can be a problem (it's a good idea to have at least 512MB for C2Cs recent versions). If your graphics card uses regular system memory, or you are using the on-chip graphics most recent CPUs have which do so, then you might not have the graphics memory problem but might (if you don't have enough actual memory for both) make the regular 32-bit related problem with the memory worse since it is allocating some of the memory to use it for the graphics.