Hello,
1/ Update the theme https://prnt.sc/C0dZy7YpvRNn https://xstore.helpscoutdocs.com/article/63-theme-update
Do not update Core plugin before the theme update next time.
2/ Read and follow this article – https://xstore.helpscoutdocs.com/article/100-how-to-speed-up-my-website
3/ As I can see, your site isn’t slow, please clear cache of your browser and check one more time.
Regards