Slow Admin Orders Grid - Magento 2.3.3 Community

We are faced with a constant issue of it taking 2-3 minutes just to load the first 20 results of the sales order grid in admin. This is with most columns deselected and only showing the most basic, id, date, name, price, status.

Overall our server is well optimised, front end is very fast.

We do have 178,000 orders which I guess is why it is so slow, but without deleting order history which we do not want to do, how can we get around this?