Sometimes a website will stop working or performing the way it once did. This can happen even if you didn’t make changes to your website.
Reasons can range from a websites domain having bad SSL Certificate signing request to coding errors and or PHP requiring updates, even malware attacks can cause performance issues.
I begin by first backing up your web applications core files and database before analyzing the servers control panel. If i’m unable to resolve the issue from your control panel i begin brain surgery on your core files by appending your theme documents to a fresh core installation.