Extreme injector v3.exe - original dll file, download here. One click to download this file. 
Repair your system. Then open Extreme Injector v3.exe and click 'add dll' buton and add dualcore.dll. Dualcore.dll is located in the same directory (drive: Farcry 4 bin).
Extreme Injector V3.6.1 By Master131
Apply dual-core fix First off, download the required files down below. • • • Do NOT use Xenos64.exe found with the DLL files, as it doesn't work - delete the file. • Copy all the files from above to /bin/. • Copy and paste batch lines into a empty batch file and save it somewhere in /bin/, I named mine to FarCry4Launcher.bat. • Rename the extreme injector executable you just extracted to ei3.exe or adjust the script - it is up to you. • Add ei3.exe as an exception in your anti-virus program, or it might pick it up as a riskware.