The website is very slow after use.

Hello,

Thank you for getting in touch with us!

Our plugin needs to parse the entire HTML of a page in order to serve translations, so it can be memory intensive.
But it usually doesn’t impact speed loading times and you can also cache translated pages, in which case they shouldn’t be processed by PHP at all.

We recommend you use a caching plugin. Cached pages are not processed on every page load, only on the first one.

Automatic translation will slow the page down on the first load, so the PHP will wait for the translations and then show the page. This only happens once or if you add/change strings.
Also, we have a article that explain pretty well how TranslatePress differs from other translation plugins based on loading speed: https://translatepress.com/top-wordpress-translation-plugins-compared-based-on-page-load-time/

20 MB does not seem like an unusually large table size but you could check it for duplicates. In case the tables contain duplicate entries, you can use the remove duplicate rows function from the advanced settings of TranslatePress.

Best regards,

I use the WP Rocket plugin, but as long as I click on a translated page it is still very slow, and the cpu takes up 100%. Can you recommend any cache plug-in compatible with your plug-in?