Have you tried running the game in vanilla setting? No windower or ashita?
yes the long load time to start the game is still persistant without windower or ashita, the other part is not, but then again I dont change gears for actions without it, I am currently trying with out a few unnecessary addons loaded to see the result, but it seemed everything was exacerbated in dynamis to nearly unbearable levels.
Edit: Currently doing VW and Im getting 0 stutters from GS will keep testing and see, however in VW its just me and my trusts so idk.