Make sure you didn’t somehow cap the fps.
The way the engine does it is murk up the rendering pipeline with a delay, so fps limits can look almost undistinguishible from any redering issues.
If you adjusted the streaming pool via command line, there’s a very real possibility you misstyped the value to use. As in KB instead of MB or similar, so maybe check that 3 times too.
All else fails, start a new peoject, slowly migrate assets until it breaks agai so you know what caused it…