forced synchronous layouts

When I load data into the widget, I get a lot of “forced synchronous layouts” in the timeline.
All of them originate in cesium.

Any idea why and how to solve this?

What browser and profiling tools are you using? I see no such messages in Chrome’s timeline profiler for example. If you believe there is an issue in Cesium, please provide all of the details and any code needed for someone else to reproduce it.