My DD was advanced at preschool. She is a bright kid who loves a challenge, and enjoys learning new things but I wouldn't call her gifted or anything (except in the school 10% sense). So for example, she started showing an interest in letters at 2, started learning to read at 3, and was reading Enid Blyton by the time she started school. She also taught herself to tell the time to the nearest hour at 2yrs 8 months. DH and I were shocked at a scan one day to see her pick up a tell the time book and just go 'one o'clock' etc...
She started school at 5, and her first school was fantastic. If DD gets bored with something, she just switches off and says she can't do it. She fooled the teacher with that for a couple of weeks, but once the teacher sussed her out, she had her own special book in reception that the teacher put extra challenges in for her, and things for her to do. She also went out and had lessons with the deputy head two or three times a week. This was with a couple of other children who were also ahead. She loved this school, and they really brought her on. She got straight 9s in all her early years profile, and I think the school really worked with her, and she loved the extra challenges that she had.
Then we moved house. That school didn't really push, her in fact they held her back. They put her back in her reading - yet when I questioned why, they never said it was to do with her abilities (and my teacher friends looked at her reading, and they thought she should not have been put back). But that school didn't push the children. Without a challenge, my daughter lost interest. She lost interest in school for a very long time, and I think underachieved. At the same time, she was chosen to compete in gymnastics and she threw her attention into that. I think she likes that because she has to work hard to learn a skill, and when she's learnt the skill she moves on to the next one. This challenges her and she thrives on the challenge. She is now in squad and trains 18 hours a week. But, the combination of enjoying gymnastics and finding school boring wasn't great. So now, she never bothers to learn any of her spellings (but usually gets most if not all of them right), refuses to do any extra work for school, optional homework or anything. Even getting her to complete the homework the night before it was due in was a hassle. I spoke to the teachers, but think because she was coasting so much, that they didn't push or think she needed pushing. In their eyes, she was just average I think. Then the school got a new head and she brought in regular assessments to the school. Suddenly, my daughter has been put on the Able register at school, and she now gets extra challenges in English to bring home and complete. For the first time in years, she now wants to do homework. She is now interested in school again, and she loves the extra homework that she gets. Even her teachers have said that she has 'started to get her sparkle back'. She's year 4 now. In some areas, I think other children have caught up and even overtaken her. But, what I find is that whilst she might not be the brightest, she does find that she can sail through school without working or trying hard. School does come easy for her and she puts in little effort. Although I do worry about the habits she is forming (I'm a teacher myself), I try not to stress about it too much. At the moment, she has a nice balance - she does the minimum at school and she very much enjoys going off to gymnastics which she does work hard at. This will have to change in due course (when she starts getting more work at secondary school etc), but as long as she doesn't fall too far behind, then I am happy.
Sorry that was very long. But the upshot of my daughter's experience has been that she has loved school / flown when she has felt challenged, but has switched off / done the absolute minimum when not pushed. I think getting a good school is very important. Certainly my daughter is not one to 'entertain herself' if the school does not push her.