I'm having the exact same issue flying over the Florida Keys. If I let my plane sit for about 20 minutes, the textures load beautifully, but as soon as I take off and fly around, they immediately get blurry. Tried turning my FPS down from unlimited, even to 99 like you, and my FPS would drop to 10-20 with constant stuttering. Not 100% sure why Unlimited works fine but anything I set my FPS limit to makes it unmanageable. Any help would be appreciated since I really would like to experience Tileproxy.