1. A concise explanation of the problem you're experiencing.
I load 60000 boxes to simulate the dynamic change of surface. When i add SampledProperty to box.dimension, then crash the browser. So how could add property to 60000 boxes?
2. A minimal code example. If you've found a bug, this helps us reproduce and repair it.
3. Context. Why do you need to do this? We might know a better way to accomplish your goal.
4. The Cesium version you're using, your operating system and browser.
What error do you get? Do you have a Sandcastle example (https://cesiumjs.org/Cesium/Apps/Sandcastle/index.html) so I can run this?
The long term solution to this is a vector format in 3D TIles (or you can convert your geometry to glTF and tile it that way), there’s some discussion on this here: https://groups.google.com/d/msg/cesium-dev/GEndY5WwAu0/TRt8ksKsEAAJ
In the mean I would recommend optimizing it by showing only what’s available in any given view, to visualize subsets of the data instead of all the data at once.