I'm sure the server hardware is not a problem. The full dataset is 150 GB and the server has 64 GB RAM, most of which will be never requested. So I'm sure that the used tiles would actually get served from OS cache. If not, it's on a RAID 0 NVME SSD, connected locally.

What I've been referring to is the fact that even unlimited 1 Gbps connections can be quite expensive, now try to find a 2x40 gig connection for a reasonable money. That one user generated 200 TB in 24 hours! I have no idea about bandwidth pricing, but I bet it ain't cheap to serve that.