Background of the issue:
I am trying to resolve severe backend issues with very slow loading and saving speed on the website jackpotlotteryonline.com. This may be related to the thread https://wpml.org/forums/topic/loading-speed-across-multiple-installations/. I was asked to create a new thread. The site uses a custom theme developed for a specific purpose, so changing the theme is not an option. The WP installation keeps sending emails saying "WordPress caught an error with one of your plugins, WPML Multilingual CMS."
Symptoms:
An error of type E_ERROR was caused in line 193 of the file /var/www/vhosts/jackpotlotteryonline.com/httpdocs/wp-content/plugins/sitepress-multilingual-cms/classes/records/class-wpml-tm-icl-translations.php. Error message: Uncaught InvalidArgumentException: No translation entry found for query: s:34:" trid = %d AND language_code = %s ";a:2:{i:0;s:4:"3769";i:1;s:2:"hu";} in /var/www/vhosts/jackpotlotteryonline.com/httpdocs/wp-content/plugins/sitepress-multilingual-cms/classes/records/class-wpml-tm-icl-translations.php:193
Questions:
What can we do to fix this?
How can we resolve the severe backend issues with slow loading and saving speed?
Reference to our recent chat, I need to take a closer look at your site. So I request temporary access (WP-Admin and FTP), preferably to a test site where the problem has been replicated.
Your next answer will be private, to share this information safely.
Also provide detailed steps to reproduce the issue and links to pages in the admin and on the frontend.
IMPORTANT: Please take a complete backup of the site to avoid data loss. I may need to activate/deactivate plugins also.