Fix Recent WordPress Site Issues -- 2

My WordPress site has stopped behaving as expected and the problem began within the past week. Pages that used to load instantly now misfire, and some elements do not render at all. I am not sure whether the fault lies in the design layer, a rogue plugin, or a deeper functionality conflict, so I need a sharp-eyed WordPress troubleshooter who can quickly isolate the root cause and restore normal operation.

Here is what I need from you:
• Audit the installation, themes, and active plugins to pinpoint the fault.
• Correct the underlying issue—whether that means rolling back a plugin, repairing a theme file, or adjusting server-side settings—without disrupting existing content.
• Verify that all public-facing pages load correctly on desktop and mobile once the fix is applied.
• Provide a brief summary of what went wrong and the steps you took so I can prevent a repeat.

The site is hosted on standard WordPress hosting (cPanel access available) and uses a common premium theme, so you will have SSH/FTP, phpMyAdmin, and WP-Admin credentials to work with. Please let me know your estimated turnaround time and any similar rescue jobs you have handled so I can decide quickly and get the site back to normal.