Open the Ubisoft Connect application on your PC. If you don’t have it installed, you can download it from Ubisoft’s official website.
Released in December 2014, approximately one month after the game’s disastrous launch, Patch 1.2 was the second major post-launch update for the PC version of Assassin’s Creed Unity . It was not a minor hotfix; it was a substantial overhaul addressing hundreds of bugs, gameplay mechanics, and—most importantly—performance optimization.
Resolved various flickering issues and performance drops for users running NVIDIA SLI or AMD CrossFire setups.
You can check your version in the bottom corner of the main menu. If it's 1.5.0, you already have everything Patch 1.2 offered and much more. 3. Making Unity "Modern" (Beyond 1.2)