I'll assume we're talking about restaurants in general and not just fancy ones, correct me if I'm wrong.
For me, noise is also a problem to a certain extent. Normal noises of people eating and having a conversation aren't a problem, but if there are some really loud people, usually little kids or a group of teens, it gets on my nerves.
As for the place being crowded, it doesn't bother me as long as the place isn't so crowded that I can't find a seat where I don't have to sit next to a stranger. Even if that happens it doesn't usually cause any kind of melt down, though. Also, crowded means more noise and even if everyone is talking normally it can still be too much. Usually I take my time eating and go things over in my head, but if it's that kind of situation then I focus on eating and leave as soon as I'm done.
Waiting can also be a problem for me... ten to twenty minutes is very basic and while it can be boring or annoying, it doesn't cause any big problems, just... if it goes well beyond what I'm used/what I expected it to it leaves a bad taste (figuratively.) And of course, it adds stress if I'm in a hurry.
Finding something to eat that I like is also a problem sometimes. If I go somewhere alone then I can just check the menu and if nothing sounds like I'd like it then I just leave, but if I'm with people I have to go with what sounds the best even if nothing actually sounds good or not eat at all.
Ordering used to be a really big problem for me in my early teens. I think it was mostly because we lived in a rural area, so everytime I ate out it was with my mom/dad/sisters/some relative etc. and I didn't really know what to do since I hadn't had a chance to practice. Of course I could've learned by following how others did it (and that is how I later learned), but that hadn't oocured to me until after I had to order on my own a few times. These days it's only a problem if I have to ask some specific questions about what I'm ordering, like if it's suitable for a lactose intolerant like myself or if it's possible to leave out the tomatoes. This becomes even more akward if the person taking the order doesn't know and has to go ask someone.
I also have a problem with trying new food, mostly because I don't want to pay for something when I don't know if it's worth the money or not, but I also don't like the idea of having to leave things I dind't like after all on my plate and getting comments on it.
Going to restaurants I haven't been to before is also a problem since I don't really know what's good and what's not, or if the place has anything good to eat in the first place. I also tend to wonder if it's okay to ask them to leave something out that would normally go to my food or not.
Formal restaurants are also scary for me, especially since I never go alone to those. When it comes to junk food or normal restaurants I usally test them on my own and confirm that the menu has something good to avoid embarrasing situations before going with anyone else. However I can't really afford formal restaurants on my own and am not exactly interested paying a lot about something that I could easily make at home for a lot lower price. So, when I go to one there are the new place problems plus the problem of how to act differently. Last time I went to a formal restaurant with my family, the waitress brought us a can of water and other drinks to the table. I took the can and poured a glass for myself when she was serving the others at our table. By the look on her (and my mother and half sister's) face I concluded that I did something wrong when it came to etiquette... I suppose I was supposed to wait for her to pour me a glass.
Also, there's this thing about my more or less weird eating habits sometimes, like the way I eat a hamburger. I always eat the edges first. If I had a reason when I started eating that way then I've forgotten it by now, but I still do it. Sometimes, when I'm in the company of someone who doesn't really know me yet and who I don't want to think of me as too weird to hang out with I force myself to eat normally, simply because that's the easiest way to handle the situation.
So yeah, I have many problems that someone might find weird but whatever; that's how my life is. And this thing with restaurants is just a tip of the iceberg.