can't help u with that issue that's not a server side issue
that sounds more like a hardware isue on your side.
only tip i can give is check your preferences/graphics settings and lower down your general & draw distance settings.
if this doesn't work consider using a lighter and more stable viewer like alchemy viewer or similarity viewer (if u use a firestorm build viewer.)
the way how phoenix firestorm render mesh can be a double edge sword and i don't recommend using this viewer at all. but its a personal choice of the user.