Extreme lag from DM side

I ran a 5e game last night for the first time. When I've used Roll20 before as a player or when prepping for this game, I've had no usability issues. However, when running the game for 4 other people last night, Roll20 slowed to the point of 3-10 seconds of lag between every action. My players didn't notice any lag from their side. I have a beefy gaming computer and I'm running Roll20 on Chrome with hardware acceleration enabled, so performance should not be an issue. I've also disabled audio/video through Roll20 as we're using Discord for that. What else can I do to fix this?

There are a number of things that might be going on. Using Advanced Fog of War and Global Illumination simultaneously is the common culprit for the behavior you describe. Beyond that, it's hard to diagnose with the info given. Was it a huge map with many pieces and tokens? What was the DL setup? Did you have many characters with dozens of spells on their sheets? There are a lot of possibilities. If you could give more info on your setup and what you tried to fix it, that might help.