Illustration by Hugo Herrera / The VergeA few months ago, I downgraded my internet, going from a 900Mbps plan to a 200Mbps one. Now, I find that websites can sometimes take a painfully long time to load, that HD YouTube videos have to stop and buffer when I jump around in them, and that video calls can be annoyingly choppy.In other words, pretty much nothing has changed. I had those exact same problems even when I had near-gigabit download service, and I’m probably not alone. I’m sure many of you have also had the experience of cursing a slow-loading website and growing even more confused when a “speed test” says that your internet should be able to play dozens of 4K Netflix streams at once. So what gives?Like any issue, there are many factors at play. But a major one is…