I'm so sorry you're going through this. I can only suggest you propose having one day the way you plan it and the next according to her time-scale and so alternating between her way of drifting along and your way of actually getting the best out of your holiday. I would not have coped with hanging around waiting for someone to finish a fag, so I think you are being very patient. I would definitely be at the ultimatum stage by now. "OK I'll wait five minutes then I'm going." Then go. Let her find out that she can't have her own way all the time. However, in my experience, this will only lead to her becoming sulky and making more difficulties...
It won't cheer you up to hear that, a few years after the death. of my husband, I went on holiday with a friend. A fairly expensive long-haul which I agreed to for her benefit. After that I decided I would never go away with anyone else again! Seriously! What's more, 7 years on - I have only been away on my own and have had a great time! I endured such dreadful experiences of behaviour I never dreamed other people would do when I was away with this friend.
In the end, I decided the best measure of whether a person is just marginally bearable to go on holiday with was how they used the towels and the bathroom. She used ALL the towels every day and stayed in the bathroom each morning and evening for so long that I had to take the lift to the hotel foyer and use the public loo, even when I'd just got out of bed.
So I sincerely sympathise, indeed empathise with you. It is hell. The only way to get through it and home again without a murder occurring is to drop all your expectations of doing the things you would like to do on holiday and think of it as a psychological experiment. Or a TV show where people are sent away somewhere and made to live together to see if they will kill each other. I wished I had written down all the things that happened or better still had a secret camera because I might have made some money from writing a book about it.
Going away with a friend is the worst idea I've come across for having a holiday. This one ruined everything we did. She "knew everything" but really didn't, which wasted hours and hours especially when she insisted on "knowing" the way to go all the time and was always wrong and - sorry! but I was always right (I actually do have a good sense of direction) but she would never listen to anyone else! I would have coped with going along with her some of the time, but all the time, every time we were deciding which way to go, knowing that she had never been right and I always had, but still she insisted we had to go the way she said....
Even on the long haul flight home she drew her knees up onto her seat with her bum pushed in my face and farted all the way home. She put her hand luggage at my feet and refused to move it, and made me hold her hot tea until she had finished eating.
Never, never, ever, ever, go away on a holiday with a friend.