iTunes playback issues and video lag

[Shall1000]

Hi

I have been running a music quiz for family and friends on Zoom for nearly two years, and these have largely been successful apart from a couple of recent issues I have met as the host:-

1) If I view the participants when the iTunes music is playing, playback is affected with stuttering.  The only way I can  overcome this is to view the iTunes screen instead of looking at the participants.

2) The video of me as host suffers badly from lagging - the videos of other participants are unaffected.

Additional info - the total number of participants is only 8, and my own broadband speedtest is around 100mbs download, 40mbs upload, which I think should be OK.  I use a separate USB video camera which otherwise is excellent, but I have removed all enhanced video features without curing the lagging.  Also, both issues seemed to creep in at the same time, towards the end of last year, so not sure if an update caused the issues -  currently running version 5.9.3 (3169).

Thanks for reading, and any help fully appreciated.

Steve