I will be writing another guide for AC3 Remastered, that shares a common fix to this game. This fix has been tested with the base Steam version of the game, but should work with any special editions and on any client.
NOTE: This fix also works with the Desmond's Journey Sequences, and the Lost Archive DLC. However, those two sections of the game use a different executable than the main game, so you will have to apply the fix again every time one of those executable's load. This does mean that you will be applying the fix for all 5 Desmond's Journey Sequences separately.

1. Launch AC Revelations through Steam or whatever client you are using to play.
   
2. Press ALT+TAB to return to the desktop.
   
3. Open the task manager using CTRL+SHIFT+ESC.
   
4. Head over to the "Details" tab,
   
5. Right click the executable, typically towards the top of the list if sorted alphabetically.
   
6. Click "set affinity."
   
7. Uncheck ALL Cores except Core 0.
   
8. Click "OK."
   
9. Right click the executable again, and click "set affinity" once more.
   
10. Re-check ALL CPU Cores.
    
11. Click "OK."
    
12. You should be able to close Task Manager, and ALT+TAB back into the game, but now with even smoother and more consistent performance!

PLEASE NOTE: THIS FIX MUST BE DONE EVERY SINGLE TIME YOU LAUNCH THE GAME!
Hopefully this guide has helped you solve any issues you are having with stuttering and/or low FPS in a game that has no right performing poorly in 2020. I would appreciate you listing this guide as a favorite and leaving a 5 star review if it did help in some way. I will be making a guide for AC3 Remastered as well, so stay tuned for that as this game has similar performance/stutter issues.