I'm not experiencing the slow down as described. I do have issues with slow dice rolls on weekend evenings, but nothing while simply opening a sheet or game during prep time. Some things to look out for: Extremely large campaigns with hundreds of characters. Extremely large maps running Dynamic Lighting (any variety). If running AFoW or Explorer mode, check for characetrs with extremely long sight ranges, or if AFoW, make sure Global Illumination is not checked. If running Firefox (mostly), turn off Autofill and Autocomplete. All of the above are known performance killers. You can also try all of the standard triage I'm posting below the line. Could you please carefully work through these steps of our guide to Solving Technical Issues ? Step 1: Make sure to use the right browser Please check if these issues persist when using both Chrome and Firefox. Step 2: Ensure that there are no extensions/addons interfering with Roll20 Please disable all add-ons/extensions. Step 3: Clear your cache If none of the above succeeds, please thoroughly work through Step 4 . (Don't forget the complete Console Log!)