All right, I will try to keep this as simple as possible.

Step 1 - Launch Far Cry 4
Step 2 - Once you are at Main Menu press CTRL + ALT + DELETE at the same time.
Step 3 - Select "Task Manager" from list of options.
Step 4 - Minimize Far Cry 4
Step 5 - In the "Processes" section of "Task Manager" locate Far Cry 4.
Step 6 - Right click on Far Cry 4 and select an option "Go to details".
Step 7 - Right click again on Far Cry 4 and select an option "Set Affinity".

Step 8 - Okay so this option depends on which processor you are using, but for me what worked is disabling all of CPU cores beside cores number 8, 10, 12 and 14.
Basically rule of thumb for me that worked was disabling CPU core 0 always, and than leaving only four of last even cores enabled.

Step 9 - Close Task Manager and put Far Cry 4 into Fullscreen mode again.
Step 10 - Start playing the game and enjoy the higher amount of FPS than you had before.

!DISCLAIMER!
Keep in mind that sadly you will have to do this every time when you launch the game, since it does not save it self. However the good news is that after a few tries you get used to this, and can perform this within a matter of seconds.