i think i found the solution, i had tested it and it works faster now
if successfully load the write a post page after a long of freezes, press the ‘custom field’ option down there
and for me, a long list pops up,
i don’t know much about writing a script but i sit there and keep on deleting those custom fields, some few hundreds of them because i imported my old posts from the previous box.
and after that, everything is fast again!
happy trying.
please tell me if this method works for you!