Slugish admin area after 5.3 update + classic editor bug

Hi,

After updating to WordPress 5.3 the admin area loads extremely slow. I tried purging my host cache, browser cache and even tried different browsers. The problem is still there, no matter if I’m editing a post or navigate through different parts of the admin area, the pages take a lot of time loading.

Also, I am using the Classic editor and only the Visual mode is working; clicking the Text tab doesn’t do anything.

Thank you