At my polling place checking in is what takes the longest. We had about 20 booths to vote in (black felt tip fill in the bubble) and only 3 races. Only a few were in use when I went in, but there were lines to check in. DH had to wait for over an hour in the rain when he went before work, and there have been lines most of the day, I got there during a lull.
But we have to go in and get in line by the first letter of our last name: A-D, E-K, L-R, S-Z . Fortunately my line only had about 5 people in it. But we have to go up one at a time, show our ID, wait for them to look through the book to find us. They we had to state our full name and address, she reapeated it back and they recorded a voting number. Then we get the ballot and go to the booth to mark our ballot and then take it and deposit it in the vote counter thing.
I have had roughly this same procedure in all the places that I have lived, and the nice people working the polls are usually elderly so they don't move too fast when looking up the names. I think that is part of what really holds things up. And only having one book for each section of names really slows things down. I don't know if they don't have enough poll workers or what. The line for the S-Z was really long when I was there, wrapping around the room and almost out the door. But A-D had no one in line and was just hanging out.
I would love to volunteer to work at the polls but the kids are out of school that day so I have to wait until they get older.