I wanted to let everyone know of a recent experience I had with the new Preview app on my M4 11 inch iPad Pro. One of my main use cases for my iPad is reading and marking up large documents with the Apple Pencil. I tried this using the Preview app. The pdf was just over 1100 pages. I realize this is a large document but pretty average for me. The iPad got so hot, I couldn’t hold it and Preview crashed twice. I pulled the same document in PDF Expert. The iPad cooled off after a few minutes and had zero problems with the document. I will be sticking PDF Expert for now.
5 Likes
The next time I have an 1100-page PDF, I will test it. But I hope I never have to test an 1100-page PDF! 
3 Likes
I used it to read a 2626 page pdf no problem! It is mostly text, hardly any graphics or photos, but I was surprised how smooth the scrolling was and how quickly I could jump to a specific page. No crashes and the iPad never got hot.
FWIW, I really love PDF Expert for PDF markup. I find the UI super effective for this purpose.
I’m using Preview more for image conversions though.