It may not all be on the client side. I've found that a number of the problems I've experienced in my games have to do with networking. As a former systems programmer, specializing in networking, I can see evidence that a lot of the problems with voice, video, 3d dice, opening pages, etc. are, to at least a majority extent, networking issues. I could go into detail but it's probably more than people want to see here. Suffice it to say that client-server methodologies are very complex and, more often than not, it's receiving the data on the client side that's the problem, not rendering it. But, this is all irrelevant. The bottom line is that I doubt that Roll20 can fix the problems. Whether they are networking, or client side issues, they would be very difficult to fix in a way that will work for everyone. This is why a lot of people have moved to other vtts that don't rely as heavily on browser technology, or would have fewer problems from networking because of the way those vtts work.