The specs are what matters first. VPS server can be in the cloud, a cloud server can be a dedicated server or a shared server. Process, RAM, type of drives and size, speed (RW Access times) and redundancy with plenty of backup.

If you have a dedicated server, great! But if that dedicated server is from 1990, too bad for you. Chances are,, the processor is super outdated, the RAM is equivalent to what my ear pods use to connect to Bluetooth and the hard drive probably has less space than my speedo after holiday dinner at grandmother's house.

Now if you have a shared server or dedicated server and the latest Xeon processors and 16 or 32 gigs of ram, some solid-state drives, etc, and it's a dedicated server? You will have some very happy members. Shared server....it will run pretty good. VPS? Same as shared but with a more dedicated feel because you have the ability to install and enable php modules, different software, etc because you are setup with a "server" running in your own instance...so it will run pretty good and feel good but it's still sharing the real server's hardware resources.

So to answer the question, UNA can run on shared, VPS and dedicated. Depending on the number of members you have, the number of customers using the server your hosting company has your account on, and the server's hardware specs will really determine how well your site will run if you are on a shared or VPS account. If you choose to pay for a dedicated server, choose your hardware wisely and make sure you understand the difference between managed and unmanaged server before you choose your plan. Then, UNA will run excellent and you and your members will be happy.