GTA V Stuttering issues

[Cola]

Just to be completely sure, did you update the graphics driver? I updated mine to the AMD Beta one today, and now it runs fine. I get 45-70 FPS from a 6 year old AMD Phenom II X4 955 3.2GHz Quad-core processor, 12GB of ram and an R9 270X. Ironically the GPU is sitting at around 30-40% usage. I run the game scaled down to 1440x900 with everything on medium. (FPS > Graphics any day )