I would just like to share a temporary fix that my faction has discovered for the FPS issues in Cyrodiil, keep in mind this works for about 80% of players and not everyone, also it is still possible that your FPS will crash again however it GREATLY reduces the chances, so all you have to do to is go into your settings menu and then click Audio and turn all of your sound options to OFF, then restart the game completely, after using this method myself i had no issues with my frame rates for 8 hours after which they crashed again and I simply re-logged and have had no trouble since, Good-luck hopefully we can all soldier through this until Zenimax is able to resolve the issue