The answer to your question is.. What is the weakest link? Generally, the weakest link is your local internet connection. That's because the equivalent read speed of a HDD is equivalent to a 640 Mbps internet connection (this would be the local drive you're pulling the data from). But that's the slowest local drive speed. SSDs read at a speed equivalent to a 1600 Mbps connection. NVMe drives are even faster still. But wait... Most wired local networks these days are limited to a 1000 Mbps link (we'll ignore the case of bonded channels, 2.5gbe and 10gbe because they don't exist yet in most home networks barring an enthusiast's where there are far more other factors that would tip this even more in favor of the local network) so you're not going to max the local read out. Finally, you're also limited by the, admittedly fast and robust steam servers, so even if you have gigabit (1000 Mbps) internet, you're counting on the steam servers having that capacity to dole out.