I did a clean install of Windows 10 pro, and it seems to have created massive input lag when connected to an external monitor (TV). The only tool I have at the moment to measure the input lag is running a stopwatch on a cloned display, and recording both screens with my phone. But if I don't know the input lag of my laptop monitor, then I can't measure the input lag of my TV (I can only measure it in comparison). I just want to confirm this is a Windows issue and I'm not going crazy (I need the actual input lag I'm seeing in order to compare it to other devices).

I wiped the recovery partition, so I have no way to revert back to Windows 8.1.