Honestly, if he didn't have some issues with anxiety, I would move him at mid year-- unfortunately, given that he's high strung, it would probably backfire.
I wanted to remark on the quote above. I had a similar situation in K last year and decided to stick it out because of how sensitive my DS was and how, in my mind, tearing him away from his comfort zone/much loved friends mid year might scar him emotionally. Fast forward to this year, I changed schools and I told him how I waited to move him to a different school and he tells me that I should have just pulled him out in K! He said that if he had known that he had an option to go to a "better" school, he would have asked for it himself. So, please ask your DS what his opinion is about changing schools.
Good luck.
