I moved my 2 girls 2 years ago - DD1 was year 5 DD2 year 2. Although they are DD1 and 2 there's DS 1 and 2 above them, so I've experience of school iyswim
DD1 wasn't getting challenged, work was boring, and we'd already moved her in year 2 due to a house move, from an absolutely brilliant school to be fair. I knew how much better school could be for her, I knew she didn't have to be bored and fed up all the time.
DD2 was not learning well but was also getting the crap kicked out of her every day in the playground. She would get punched, kicked,pushed into walls. She's small and at lunchtime no one would sit with her because she was small she was made to sit at the table with the nursery children (she was P2)
Many many visits to the school, the head refused to believe me, children who were doing the bullying were children/grandchildren of people on the board of governors and from prominent local families.
Cut a long story short, there was an incident where a rope was put around her neck and the boy said "I hate you I'm going to make you dead" and he pulled both ends to choke her.
Another child saw, ran for help. Went in to see useless twunt headmaster and he said she obviously couldn't cope with normal playground rough and tumble... WTF
So, went next day to see next closest school, it was a wednesday, lovely atmosphere and I just knew right away it was a million times better, head of that school suggested bringing girls down after school, I did and DD2 said "I love this school can I start tomorrow"
Not quite lol, but she did start on the friday - took them into the old school on the thursday, told head i wanted a word and he blustered I said I'm moving them what do I need to do. He tried to dissuade me, but I stuck to my guns.
Anyway, when DD1 came back from a visit a lunchtime her class stood up and applauded that she was leaving (and the teacher let them)
DD2 came home with a card, made by some of the children, that said "We won't miss you and never forget you have foes"
They never went back to that school, started their new school on the Friday (what a ridiculous day to start school) and have never looked back.
Oh and the confrontation between me and the old headmaster on the friday about the card was rather epic.
Oh jeez I've written war and peace lol
I'd say move em they'll settle quick in the summer term and there's loads of stuff to do to help them make friends.