FPS Drop

[x--v--x]

I'm running gta v with max setting expect MSAA because if enable it to X8 the game will drop a lot fps, how to fix ? here's my pc specs :

CPU : Intel core i7-8700 3.20GHz
RAM : 16GB
GPU : Nvidia GeForce GTX 1080 Ti 11GB
Monitor : 2560 x 1440 Max refresh rate 144Hz

Should i upgrade my GPU ?

Note : I don't have heavy mods installed