How to edit template in WordPress admin?

Question

WordPress

In the latest versions of Wordpress, a convenient code editor with syntax highlighting has appeared right in the admin panel, i.e. it is very convenient to edit the code there.
But as soon as I made the changes, the site freezes for two minutes, the page is not updated, it does not give errors, just endless loading. And so with each editing of the code, and before that everything was fine. What is the reason?

Answer 1

1) No need to edit templates through the admin panel (IMHO). It is not comfortable. Everything via ftp, via sublime, notepad++, etc.
2) Eliminate conflict with plugins. It is possible that some of the plugins are in conflict, which leads to endless loading.
3) Enable wp-config.php debug and check
4) View errors in the browser console during the appearance of "infinite" loading