The loading of a static content page versus one whose content has to be made on demand will show a considerable variance.

Depending on complex the query is, your server may be making many calls to the database. In turn, the speed of this will rely on whether the database and other objects are cached, by software like Redis, Varnish and Memcached.

For example, my server has all three of these, with nginx as the proxy server. Redis requires the installation of an Object cache in WordPress.

The tuning of a server for search intensive sites is a dark art, and this is outside the scope of our technical support.

If I may ask, how many posts does your site have, and how big is the form?

When working in the admin, I notice that that pages load very slowly. This is very unusual for WP Engine hosted sites. They normally load almost instantly. This is not improved if I deactivate our plugin. Something very odd is going on.

Normally, I would say use a WordPress cache plugin to speed up front end loading. The simplest to set up, and the fastest (by only the tiniest of margins) that I have tested is Breeze. But, WP Engine must surely offer you server side performance tools as well? It is there that the issue originates I think. Maybe the database is not being cached, forcing requests to go to the actual disc drive?

As I said, all this is a dark art, and I am not the best person to be asking this of. I am not familiar enough with WP Engine hosting (other than to know that they are an excellent hosting company).

Thanks for letting me know. I will close this thread for now.