I was having the same issue, and I managed to solve it for Chrome. In Chrome, for some reason, hardware acceleration was disabled, forcing my CPU to carry the rendering load and thereby causing lag when interacting with the VTT. To make sure hardware acceleration is enabled: 1. Launch Chrome. 2. Type "chrome://settings/system" into your address bar (no quotes, obviously). 3. Ensure "Use hardware acceleration when available" is enabled. 4. Relaunch Chrome. Hope this helps!