Starling RenderUtil.clear(Context3D.clear()) takes abnormal amount of time to clear

In some cases which I am not aware of yet why and how RenderUtil.clear(Context3D.clear()) takes abnormal time to clear. This was tested with AIR 29 and iPhone X.

This happen from time to time and I am not sure what is the cause of this. Once the character in game dies and GC kicks in it returns to normal.

This is the function in Starling that is used to clear context:

https://github.com/Gamua/Starling-Framework/blob/365ece4199385d2e197219a2fa57114b42cb818d/starling/src/starling/utils/RenderUtil.as#L39

Take a look at the screenshot:

https://ibb.co/kRpSnH