http://www.reddit.com/r/Planetside/c...client_to_fix/
"For you @planetside2 folks having issues with the new client, we are rolling back to 32 bit to resolve a few issues."
The 64bit version was remove for it being crashy and unplayable for some players. But there are reports as well of the 64bit helping performance as well. I don't know the full details, but seems like it could have just been more sub-par PCs being bad or people not updating things for 64bit stuff.