External webcam slow and lousy on a Mac mini? I run a 2012 Mac mini using a Logitech C920 HD Pro USB 1080p Webcam with it. Recently I've noticed it's really laggy. Even in a Skype test window or camera settings, it lags about a second and is very jerky.

Tests show I am getting about 1fps. I tried the Logi Capture app as suggested and it presented more settings but none helped. 

Also: audio doesn't work on it. It reports as a microphone but didn't work as one. 

Also: maybe a non-issue but my webcam device name is reported as "HD Pro Webcam C902 #2" - why #2? Some apps have a drop-down showing two cameras, this one and . 

It seems to me like it's surely a driver issue but I cannot see Logitech provide drivers, and MacOS doesn't seem to recognize webcams as a category in Settings.

One thing I spotted while researching was about the Mic issue, it talked about changing the sound settings on the device:


But, on my Mac that Format drop-down is non-editable:


That might be a MacOS version discrepancy but I do feel for whatever reason, it is not properly supported at the hardware level.
So, I fixed it. By unplugging it, and plugging it back in to a different socket! Suddenly I get audio and the video is perfect.

It's not much of an answer but it was the solution for me!