Upon upgrading to UP5, Chrome was behaving terribly. It would take a second or two to switch tabs on a very fast machine. Each time a tab was clicked, X's CPU would spike to 100%. I tracked this to this debian bug: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=682308. Basically, UP5 upgraded to libcairo2 1.12.2 and this version reverted a patch that had been in earlier versions to prevent this behavior. As of yet, libcairo2 has not been repatched in debian testing to address this problem. Some people have recompiled libcairo2 with the patch, with success.
In the bug I linked to I saw that several people claimed the NVidia driver 304.30 and higher fixed this problem, without having to patch libcairo2. I decided to go this route, and it worked.
Debian testing has already upgraded the NVidia driver. I decided to manually pull the .deb's from Debian testing and upgrade them, rather than mess around with apt sources. I think this is a pretty safe method as you are only upgrading a handful of NVidia-specific packages, and when the next version of Linux Mint comes out it will probably have newer versions than these and then will upgrade them automatically.
I went to http://packages.debian.org/wheezy/nvidia-glx and downloaded this deb for my machine (amd64) along with the packages it depends on that needed to be upgraded. So the packages I ended up downloading were:
nvidia-settings needs to be upgraded first so I ran "dpkg --install nvidia-settings_304.48-1_amd64.deb". Then I did "rm nvidia-settings_304.48-1_amd64.deb" and "dpkg --install *.deb" to install the rest. Reboot and everything worked fine.
If someone has a better method feel free to share it -- this is just what worked for me.
I'm not really sure what the official policy is for pushing packages outside a release pack, but it seems like one could make a case for this being pushed before UP6. As far as I can tell, this bug would probably affect anyone who is running Chrome & the nvidia driver, which seems like it would be a lot of people.