Tonight I had not only created a virtual machine on my server (which I host other VMs, also turned them off to test) and it was terrible. I even put it on my own machine (3950X AMD, 32GB RAM, 3090TI, PCIe 4.0 M.2 SSD at 3800Mbps) and it was still terrible. I dont know if it is the amount of patients or the size of his database (16K patients and 11GB Database), but even on my workstation being a standalone could not compete with it. I think for the size of his practice and the latest updates are just not working at all and it is time for him to switch.
My thought is, if I can play Cyberpunk at 4K no issues, encode a 4K 1 hour video in 15 minutes and my network is a 10GBPS network, with the amount of high speed cores I have and DDR5 RAM and amazing charts is still crawling, there has to be something wrong with amazing charts itself.
I think you're onto something. It's likely something inside AC.
Most server processors and going to be slower than your test bench. If it's slow for one user, it's going to be slower when you add the rest. New hardware won't make a difference.
Upgrading from SQL Express to Standard/Enterprise doesn't really make a massive performance difference given how AC is programmed. Most people end up getting because they exceeded the 10GB database limit rather than performance.
I would dig around and see where it locks and slows down. That will give you a hint of what needs to be cleaned up.