For those who ran into similar issues, it turned out that a lot of this was due to the fact that I was using the cesium viewer as a reactive element in Vue which was slowing down its performance a lot. Once I made it non-reactive, the FPS went up due to that as well as the czml reference changes I made above. Some additional information about vue reactive elements with cesium: Cesium & Vue - Performance Issue - Low FPS and Slow Rendering