My own experience: Snowglobe - I get around 35-40FPS when the sim is full (30 members no battle). The problem is that when I teleport like 5 times on the 6 times the teleport never work. So I have to close the viewer and log in again. VerticalLife - Good FPS but textures sometimes look weird on my screen. Emerald - Low fps for me 15-20, but lot of good features. I need to test Nano viewer.