Frame rate dropping periodically.
I have a similar issue to some that have been posted but its not exactly the same. Even on the menus the game will run at around 100fps and then every so often will drop to around 2 or 4 or something...
Forum Discussion
I think your after this:
http://imgur.com/a/6KJBH#87BGUaE
(Replace BF:H with PvZ; it's the same thing)
nVidia Control Panel -> 3D Settings -> Program Settings -> Add Program (PvZ) -> High Performance Processor
