Thanks for trying that.
1. If you’re using a child theme, switch to the parent.
2. If you aren’t using a child theme but have modified the parent, switch to a default theme like Twenty Sixteen.
3. If you have a caching plugin, clear the cache.
4. Install https://wordpress.org/plugins/server-ip-memory-usage/, check the footer in the WP admin and check your PHP memory usage, what percentage is it at?
5. You indeed reinstall Page Builder and Widgets Bundle without losing content.
When done, please, could reply in the form of a new topic using the form at the bottom here: https://purothemes.com/support/forum/polestar-theme/. Just so we aren’t send notifications to j, the original poster.