someonesmelon Your D drive only has 8 GB free space. Is this where Sims 4 is installed, or perhaps you've redirected your user folder there? Either one could account for the game starting slowly because of how mechanical drives work. I'm not saying this IS the issue, only that it could be. But since C has plenty of free storage, this should be an easy fix.
I also want to double-check that the new Windows account's username is standard: only letters and possibly numbers, no special characters. I meant to say so before but forgot.
Other than that, please try playing in a clean boot, with your antivirus temporarily disabled (it's safe as long as you don't do anything else at the same time) and still in the new account. Here's how:
The one service to leave enabled is the EABackgroundService, which the EA App needs in order to run. Disable the rest as described.
When you reboot your computer, go through the Task Manager's background processes list shutting down any service that doesn't absolutely need to be running, for example anything from MSI Afterburner to RGB software might still be enabled. If you accidentally kill a critical process and it doesn't restart on its own, just reboot your computer again.
Don't open anything other than Sims 4 and the EA App while testing, not even a browser window.
If this helps, you can selectively reenable services until you find the culprit, then either leave that disabled or (if it belongs to an app you want to keep using) let me know what it is so we can try to fix the underlying issue.
If the game freezes or crashes in a clean boot, please try again, except offline again.
