You can view the whole list of Patch 2 notes via the Total War Wiki, as well as preview the upcoming Patch 3, which entered beta testing yesterday.
This patch includes optimizations for Campaign performance, AI round time improvements, adds additional options and guidance for players in tweaking the settings of their game and over 100 other changes and fixes.
Full patch notes can be found here: http://wiki.totalwar.com/w/Total_War_ROME_II:_Patch_Notes
Patch 3 enters beta testing soon, with changes to battle gameplay and further improvements for specific hardware configurations.
Assistance for anyone seeking to solve issues or improve the performance of ROME II on their system is available from the CA support team at http://www.totalwar.com/rome2support.