I do not know what you are asking about

.
Do you ask about performance difference between GT2 and GT4e? Or between Skylake GT4e and KabyLake GT4e?
If the second option, as I have written, I think 72 core GT4e KabyLake GPU will be around 40% faster than GT4e Skylake(Iris Pro). We do not know the core counts, yet, they may be even higher, with better architecture, and higher bandwidth. So the differences can be bigger. But if we talk about new architecture and higher bandwidth on the same core count it should be 40% faster, but that is my estimate, because we do not know how increased bandwidth also will affect the performance of new architecture of the GPUs.