Recently, I updated the version of WordPress on my website, and that got dramatically slow. Is there the problem with the hosting or it is something wrong with the PHP version, as I updated that too.
Are you using caching and if so have you cleared the cache? Have you also updated your plugins, especially any security or other plugins? Have you updated your theme to a version compatible with your current WP? Have you tried disabling your extensions and re-enabling them one-by-one?
What version of WP?
For me, 9 times out of 10 it is an outdated or conflicting plugin issue or I forgot to update the theme to a compatible version.