How are you using onviewchange? Do you perform the hotspot manipulation every time the event is triggered? You could try implementing your own minimum interval system, such as a timestamp with the time of the last check (onviewchange would first check if it's been more than X seconds since the last check before doing the heavy stuff) or a plugin that checks the FOV every X seconds and then does the hotspot adding and removal from within itself... Where X is for example 1 second.