New answers tagged plugin-w3-total-cache
Simplest way to see what is causing it is to disable all plugins and add them back one at a time. If that doesn't reveal it, switch to a default theme. After that I'd say it is something server side. To answer your question though - caching should help but it depends on what is causing the high usage.
This is still the case in 4.2.2. If DB_NAME or DB_USER is wrong, you get the nice "Can't select database" screen from wp-db.php. If DB_PASSWORD or DB_HOST is wrong, db-error.php gets called. Weird. Without db-error.php, the nice screen gets rendered for all four of the above errors, which is a more consistent user experience (just no webmaster email).
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