Apache: Limit Traffic per domain or file

According to this document, lighttpd supports per-server and per-connection rate limits.

The linux traffic shaping subsystem, documented here, will give you a lot more control over this sort of thing, but at the expense of a much higher learning curve.

Meanwhile, another option is available since Apache 2.4.10: Proxy via Handler. See the example in the Apache documentation: mod_proxy_fcgi examples

You can also force a request to be handled as a reverse-proxy request, by creating a suitable Handler pass-through. The example configuration below will pass all requests for PHP scripts to the specified FastCGI server using reverse proxy. This feature is available in Apache HTTP Server 2.4.10 and later. For performance reasons, you will want to define a worker representing the same fcgi:// backend. The benefit of this form is that it allows the normal mapping of URI to filename to occur in the server, and the local filesystem result is passed to the backend. When FastCGI is configured this way, the server can calculate the most accurate PATH_INFO.

<Proxy "fcgi://localhost/">
    ProxySet enablereuse=On
</Proxy>
<FilesMatch "\.php$">
    SetHandler "proxy:fcgi://localhost:9000"
</FilesMatch>

This allows RewriteRules and authentication in .htaccess files. After all the rewriting is done, the request is passed to php-fpm.