Ineffective task scheduling on two GPU

Using Win 11 Laptop with 1. Intel Iris Xe Graphics and 2. Nvidia 3080Ti. (16GB Memory) Preset of ME for Video Rendering is "Mercury Playback Engine - GPU Accelleration".

During Rendering Video Decoding is done by one GPU, Video Endoding is done by the other GPU. But which will be taken varies from Job to Job. But - even not all times - you can pretty make shue that the more heavy task (example decoding 8k) is handed to the slow Iris Xe Graphics, while encoding to Full HD is given to 3080Ti. So same job takes 50 min if 3080 is doing the heavier job, takes more than 5 h if Iris Xe is taking the heavier job. How to help ME making a better GPU choice? Or how to get Iris Xe out of order? (Deactivating Iris Xe in OS causes touble while starting Windows on 3080Ti, so that´s no go)