I know you can right-click a folder and hide the stuff under it (That is awesome) Even better would show the eyeball that a user can click next to the folder:
Yeah...it's a speed thing. If you have 1,000 items in a folder it has to scan them all to decide whether to show the eyeball as "visible" or "hidden" or "partially hidden" on the folder. We'll do some internal discussion to see if there's a way we can do this without having it take a hit on speed.