Thank you for bringing this issue to our attention. After careful consideration, we have determined that this is as designed. The SerializedObject.UpdateIfRequiredOrScript will be called on a regular basis by the editor binding system to know if any change needs to be applied to the UI. So this recurring method call is to be expected. We have plans to improve this in the future, but we cannot give an exact timeline for when we'll be able to start tackling these improvements to the binding updates.
The profiler times we are seeing with the repro project are to be expected and taking less than 1-2 ms in deep profile mode, which can add a lot of overhead (can be at least ~10x).