

If you’re up for ARPGs, simething like Titan Quest or Grim Dawn have many hours worth of gameplay.
Worth looking at as well is anything in the Monster Hunter series. World and Rise are both amazing along with their expansions and Wilds just recently released.
All of my recommendations are long-term games with many hours worth of playtime.
My browser clears history and cookies automatically when I close it. Been doing it that way for years and it works for me.
I have to login to everything everytime, but it’s worth it to me.
ETA: Because of this I don’t experience the slowdowns you mention, but it comes at the price of logins not being persistent.