Well, the biggest factor is your location. Our servers are in the Netherlands. Sometimes our respective ISP’s don’t choose the optimum route between each other and that makes downloads slow. The quality is ever changing, and all we can do is try to route around slow connections. This is why we have created alternate routes all over the world. Not the best solution, but it helps.
Our default route is Cloudflare CDN, which should be automatically routing the traffic from an endpoint close to you. Cloudflare is a very large CDN (Content Distribution Network) provider and they have many endpoints around the world to help speed the internet for companies like us. This route should be good for most of our users.
If you are still seeing slow download speeds, you can always perform a speed test from one of our alternative routes and select a different route on your Settings page.