1. A concise explanation of the problem you're experiencing.
I used CesiumJS in a React project and created a React component that contains a rotating Earth.When I left this subpage (eg returning to the homepage), this component was unmounted, but I found that there was always memory not freed, especially those occupied by the GPU process (the "Task Manager" in Chrome).
If I enter this page multiple times, the memory occupied by the GPU process will increase accordingly unless I refresh the entire page.
I also tried on other browsers（IE 11/Firefox）and encountered similar problem, with different severity. The memory will increase everytime I enter that page.
2. A minimal code example. If you've found a bug, this helps us reproduce and repair it.
Main code as below: