Major Assassins Creed Issues

[Azylacus]

I recently got AC4 and just got AC3 free from ubiclub. But when i launch both of the games, they immidiatly stop working "AC3/4SP has stopped working".

The only way to get AC3 to work is by running in in compatibility mode for Windows 98. And launching it directly from the .exe.
The only way to launch AC4 is to run it in compatibility mode for Windows 95.

The problem is that doing this is causing very bad fps drops and very low fps. My system can run games like The Witcher 3 on medium to high settings, but even if i go down to Low on AC3/4. i can't keep a stable 60 fps.

My PC Specs
OS: 64-bit OS, x64-based processor (Windows 10)
Processor: Intel(R) Core(TM)i5-4690 CPU @ 3.50GHz
Memory: 8 GB RAM
Graphics: NAVIDIA GeForce GTX 750 Ti
Storage: SSD 100GB, External HDD 3TB