You need a better CPU (that CPU came out in 2011/12) and GPU.
Even AMD's best CPU has problems with GTA V due to the old architecture, it very dated.
If you had an i7 for example you would not be experiencing these issues due to the i7 having 8 threads, clock speed and boost clock and newer architecture (Haswell ones came out in 2013).
You need an AMD R9 380/90 or Nvidia GTX 900 series (i recommend the 970) or the new GTX 1000 series (if your swimming in cash you might as well go full tilt and wait for the 1080TI) to play this game.
It is very very CPU intensive your system is not up to the task sorry.