@A_Fulcrum_Agent When you open Origin but don't launch Sims 4, do you see the same problem? Or is it only after the game loads and before you close Origin again that you see the issue? You mentioned the problem showing up before Sims 4 was open in the clean boot, but was Origin open or was this right after you rebooted?
If you can find that other mouse, it would be a useful test. The way you describe the issue, it could be due to Origin overloading the system, or it could still be something about the mouse you're using. In the meantime, you can experiment a bit.
Try using a different surface (mousepad, gaming mat, whatever) under the mouse. Also try disconnecting and reconnecting the mouse at some point after your computer boots, and separately after you open Origin.
There are two Origin tools that run alongside Origin proper: the Client Service and the Web Helper Service. Try disabling those in the Task Manager before you play. And put Origin in offline mode afterwards, but before you launch the game. Disable Origin in-game as well: hover over your username, select Application Settings, then the Origin in-game header, and disable the option at the top.