the GTA launcher shouldn't comprimise the system that much, you do have more than enough RAM to handle it.. tbh plenty of solutions to this atm
1. close unwanted programs while gaming either via task manager (ctrl-alt-delete) or advanced system care boost more which I personally recomend using.
2. make sure drivers are up to date
3. if your pc is old or situated around dusty environment / on the floor then would recommend cleaning around the motherboard (NEVER do this yourself without knowing what your doing, could blow the board)
4. your g-card is very similar to mine, and more than capable of running it, overclocked or not, really wouldn't change any settings via any 'boosting / overclock' programs.
5. apart from ASC, would recommend looking at ccleaner, and just run this at the end of every night before using ASC, as ASC can also shut the computer down so that you can just leave it be.
6. apart from that mate, would advise to clean the registry / defrag it every now and again.
7. alot of programs have 'run while the computer is idle' or some programs which will run automatically evfen when your playing GTA, no matter what system you have, this could slow it down, yet again would recomend using boost mode.
this is all i really can think of,
Take care
really wouldn't know why it would 'stutter' on reload.. never had that when on GTA, really couldn't say sorry.., would just suggest to 'give it a min' before reloading it 🙂