Hi gospel, I have the exact same problem as you where when I use the classic editor plugin it can take more than 2 minutes and after deactivating it it runs smoothly, after I read all your complaints it turns out I also feel the same thing, then do you have you found the solution?
I have a news portal website so it is very risky if I take the wrong action which causes the news to disappear, so I have to be very careful but this is the problem, hopefully I can get help soon from the relevant team