Ubisoft released patch 1.01 to tweak a plethora of features. As is usually the case with the first patch after a game is released, the patch it is very important.
“Patch 1.01 for Far Cry 3 on PC is a critical update that needs to be installed in order to benefit from an optimal game experience. The install is automatically triggered upon Uplay PC client restart or installation. If your Far Cry 3 PC game crashes upon launch, please restart the Uplay PC client and try again”, posted Ubisoft on their forum.
The patch deals with many issues players were having, improves the games stability and performance, adds a few features and fixes glitches and bugs.
You can consult the complete patch notes here