I have a file with bogus data that I can provide. The thing with it is that it contains a lot of zero bytes in the beginning and end. Standing at the very end and then opening the Search menu, it says (location 99%) Searching in the message line, and it takes a long time for the menu to appear. Maybe you can reproduce by having, e.g., a 300 MB file with all zeroes?
Standing at the beginning and selecting Search menu does not give this behavior.