With nvidia 310.19 as packaged by Arch Linux, my system runs fine. After upgrading to 313.18 X uses huge amounts of CPU and I can hardly move windows any more.
The log file of the running X with 313.18 will be attached shortly. won’t be as .gz is an “invalid file extension”. Please fix that too.
http://paste.xinu.at/gyE8Y/ (Link valid for 10 days, will reupload if necessary)