My blog can’t keep up: 500 errors all over

Several times a week, someone emails me to report that they tried to leave a comment and they got a 500 error. htaccess file at the root of my blog:

The intention was that it would entice Cloudflare to cache everything. php file:

I now use Cloudflare with the following settings: “Caching Level: Ignore query string”, “Respect Existing Headers” and “Cache: Everything”.

Source: lemire.me