Hey there Michelle, as you could witness yourself, the game is in a bad shape right now regarding optimization. Every player is going to tell you the same, that no matter what kind of PC do you have (be it NASA setup or Potato setup), you're gonna have a bad time having stable FPS, specially in crowded areas/raids.
If you are really thinking in playing back again, I'll recomend you to watch some videos of EvilDoUsHarm. He gives pretty neat tips and he even has a sort of "guide" for returning players. If you still need more information, feel free to DM me here so we can get in touch somwhere more user simpler and easy to use, like Discord, for example.
Other than that, I hope this helps.