Hi Rob,
Thank you for the details, it helps a lot. The index table engine was not enabled, so I changed that.
After doing some tests, I measured around 1.5s response times afterwards. I believe this is as fast as it can go, as even empty requests (I initiated them manually, just to see the server response) to the server take around the same amount of time. For faster reponses you may need to review the server side – disable some plugins, check code quality or switch to a better back-end server.
I hope this helps!