My iPad Pro 12.9 first gen has the same problem. But it is only down to the fact that I am editing 34mpx photos and using many layers etc. In average I am working with files 600MB. So no surprise that iPad will be sweating little bit. And don’t forget iPad Pro is not mac book pro (even though Apple is trying to say that you don’t need anything else). Overall I think iPad and affinity deserve a big respect.