Did you factory reset your phone after installing the Android 10 beta? Most people who complained about the UI being laggy found the problem went away after a factory reset. If you didn't factory reset then changing that setting is essentially a band-aid--your phone still has the corrupted data that was causing your issue but is ignoring it since you are forcing GPU processing.
Just saying, if you do this, apps like Netflix will not work. You shouldn't notice a difference using this, and this is not intended for daily use, keep that in mind.
