I've found that somewhat unexpectedly sometimes physical is faster for search.
With a physical book I might remember that the equation I'm looking for was near the bottom of a series of equations on the bottom half of a left hand page, and the right hand page had a particular graph, and this was somewhere in the third quarter of the book.
It is then just a matter of quickly fanning through that general region of the book to find it.
With digital I can do a digital search but it is hard to find search terms that don't return a ton of hits all through the book. As I read a digital book I don't get a sense of movement through it that I get from a physical book, so I'm less likely to be able to remember how far into the book what I seek should be.