Email Template takes too long to open, edit or save

Hello guys,
I’m dealing with mautic latency to open email builder for weeks now.
I’m trying to explain how the problem stands below, and if anybody has faced with it and has a solution, please let me know.

The current version of my installation is 3.1.2, and I was facing with latency on every module inside mautic. It takes too long to open the Contacts list or the Segments, or the Campaign list view.
Even turning one page back takes way too long.
So I decided to upgrade from 3 to the latest version that we have now(4.4.6).
The situation didn’t change much, the pages still take a while to load(at least less then before), but the Email Templates, as soon as you edit one of them and try to launch the Builder, the page gets stuck, trying to open the email template and it takes at least 5 minutes for the loading session to finish.

Please, let me know if there is any other solution related to this issue.