Select/Select2 hanging in Chrome / OK in Firefox & Safari

I’m having a problem - that seems fairly recent - with a form that has apparently been working OK previously.

It has a number of Select2 fields on it that have quite a lot of complex SQL to populate them.

It works OK in Chrome and Safari but recently in Chrome it seems to make it unresponsive/very slow. It can take up to 30+ seconds before the Select fields will repsond to a mouse click. This form is used/accessed from a lot of areas. It is used both as a main app (called from a menu) and also within a tabbed display.

I’ve tried going from Select2 to Select fields but that doesn’t make any difference and I’ve done all this using incognito windows to avoid cache issues. It affects both dev and prod versions.

Any ideas how I can troubleshoot it further? I don’t really understand developer mode in Chrome but I’m guessing it has some tools that might help? I expect ultimately the issue is a bug that SC need to sort out - but getting as close as possible to it will hopefully speed up resolution.

Ideas appreciated!

Chrome video: https://1drv.ms/v/s!AhYVPZRtIR2NmLUo9rDXv927hrI9BA
Firefox video: https://1drv.ms/v/s!AhYVPZRtIR2NmLUpAJ-jtGJWfSyXwA?e=yISX7t