Hi,
It’s very likely that you have a module enabled in that world that is causing it. Check the Trouble with Modules tutorial for more information.
I would also recommend testing a blank new world rather than a blank new scene, as a new world wouldn’t be affected by any lingering settings (such as which modules are enabled).
Finally, if that doesn’t help, I suggest you try in a different browser or an incognito window, in case your browser has some malfunctioning extensions enabled as well, which could affect performance.
I hope that helps.