What made you realize it was the print statement slowing it down and not the file read itself? I mean, the fix sounds obvious once you find it, but in the moment when everything is just sitting there blinking at you, how did you actually figure out where the bottleneck was? Did you just scan your code line by line and spot it, or did you have to add some kind of timer or counter to make the problem show itself? Idk about you but when I've had stuff freeze like that, my first instinct is always to blame the big scary parts like the file or the library, not the little harmless looking line I typed myself. So I'm curious what the ah-ha moment actually looked like for you.

Watched a buddy shoot a whole trip on film he carried in his backpack through three airports and every roll came back fine, not one scan issue. He just kept it in his carry on and let the bag guys hand check it when he asked, which only takes an extra minute. The stories about scanners wrecking film are mostly ancient history from the pre 2000s machines.