Hey , that shuttering problem is kinda of easy to fix :
- Go on nvidia control panel and click on Manage 3D Settings its in the first menu ,
then click on Program Setting , then find you gtav.exe or what ever its called and add it to the list and from there
just turn off all the features considering i don't know if u either have a gt 630m or gt 630 if you do have gt 630 "2 gb" then try changing the ram or your cpu.