A common use case for DynamicGI.UpdateEnvironment is to update lighting information between day and night. However, DynamicGI.UpdateEnvironment is very expensive using sky light source because currently, sky lighting and reflection gets calculated and read back from the GPU in a single frame. This can cause huge stuttering when updating lighting frequently.
Asynchronous rendering of the ambient probe would solve one of the biggest performance issue - RenderSettings.CalculateAmbientProbeFromSkybox, which can cost as much as 300ms even on a MacBook Pro. This would allow to get sky lighting updated without big performance hit at a cost of a little latency.
The best option would be to make a check box in which developer would be able to choose if he wants performance or instant change of lighting.