I am also experiencing this situation. I used to use Microsoft Edge (Chromium) yesterday, before making a switch to Mozilla Firefox. It slightly helped me, however this is not the cookie cutter performance one would think they'd be getting at the usual silver times of Roll20. It must be related to some Amazon server-side performance overload, or perhaps some dev/api features of Roll20 take up all of the bandwidth and that leaves us with nearly nothing? Who knows. Either way, another symptom of this is that marketplace packs download at the speed of 10-15 kB/s.