Does slow and steady win the race?

I have to say that out of all the people I work I actually really, really dislike ( I don't like to use the word hate but it's pretty close) only 2 of them. One of them is Valerie. She is an older woman (likely in her early 60s) and I have to be honest I know very little about her personally. I have no idea what she is like outside of work. I'm sure she has friends and family who love and care about her. And I know she has a son and grandchildren so I try to remind myself that she is someone's mother and grandmother when I am on the verge of totally losing my patience with her. Maybe she hates being there as much as I do and she's miserable while she's at work but when she leaves work she is a sweet person. (Although I have to say I doubt it). My first experience actually working with her was months ago when I started working in the morning on weekends. I found her to be nasty and extremely condescending (which I really can't stand). Like honey, we work at a grocery store, we're not performing brain surgery here so there is absolutely no need to talk to me like I'm a stupid child who is incapable of understading how to hang price tags on a shelf. But one of my other problems with her came up when I was working with her a few weeks ago. It was still early in the morning so we were the only 2 cashiers there. But she kept wandering off and leaving me there by myself. Which I was fine with because as far as I was concerned the farther away she was from me the better off I was-until there was a little rush of people (a line of about 4 or 5 people) and she was up front stocking the candy shelves--seeing these people waiting in line--but seemingly unwilling to open her lane. She finally opened and took one of the customers over to her line. I noticed that in the amount of time it had taken me to check out 3 customers she was still on the same customer she had when she first opened. Now I will admit her customer had a slightly larger order then the customers who had come through my line but her customer had been in her line for about 10 minutes. There she was chatting away and placing each grocery item in the bag as slowly as if it was a grenade she thought would go off if she didn't handle it very carfeully. I swear to god it was like a deliberate work slow-down. Her own mini protest. Again in the interest of fairness and full disclosure I will reiterate that she is much older than I am and I also learned that she has had some recent medical problems so I try to be patient and cut her some slack. It's just frustrating to be the only other working with her in the morning, especially when you're working to keep the flow of people moving and she's spending 10 minutes per customer. Maybe some customers appreciate the extra time she spends with them. Maybe slow and steady wins the race. But I sort of don't think so--I think it is entirely possible to be friendly and polite but be efficient at the same time. And I also think while most people don't mind making small talk with the cashier at the grocery store very few people want to be held up for longer then necessary, unless they personally know the cashier.