That is one of the few things where I vehemently disagree with the Chinese way compared to us europoors.
Classes under 20 persons per class have a significant increase in efficiency both for teacher and students.
Honestly while I agree with the general sentiment behind having more teachers per student, isn't there also a merit to having larger classes? The current system has proved capable of producing some of if not the best prepared students globally, for many many years.
Chinese school runs using large classes with a single, "authoritarian/impersonal" lecturer (as opposed to European style teaching where teachers develop more personal relations with students). If that sounds familiar to you, it should, because that's how universities globally are run as well. A lot of elite universities in many different countries manage to create really really good graduates using this system.
With large classes, you isolate the students and encourage them to study in small groups rather than approach things as a "whole class". It also pushes students towards learning how to study on their own, rather than being guided by sometimes overly coddling adults.
An impersonal lecturer puts out information and sets a goal for the student to achieve. Students essentially recieve an obstacle and are asked to solve it using their own problem solving skills.
That's teaching kids from an early age the expectations that will come in work and university. It's teaching them to organize with their peers, plan ahead and take responsibility over their own lives.
There are strengths and drawbacks in both models, and some European countries have achieved good results as well. Instead of just splitting classes and hiring more teachers, the best path might be to study the advances and disadvantages, then reform the existing system based on the result.
Even though I'm just an amateur in educational theory, this topic is still very interesting to me.