Stalls when scrolling, green screen, folders not showing

Lightroom Classic has been misbehaving intermittently for a few months now.  I had hoped the latest version would fix things but it hasn't. When scrolling in the Grid,or Filmstrip image display sometimes stalls for several seconds.  When importing, the folder structure of the hard drive where my photos are stored sometimes does not display in Destination, and now I sometimes get a green screen when selecting 100% view in the Library module.  If I quit LR and re-open the problems go away but eventually return.

I have the latest version of LR classic (15.0.1) installed on my internal SSD drive (2Tb with 360GB free space).  I have done all the recommended actions to improve LR performance including uninstall and re-install of LR, deletion of preference files, checked cache size is adequate (it is set at 50Gb and is on my internal SSD), optimised catalog.  Graphics processor is on auto.   I have deleted any unused plug-ins. I have a Mac Studio M1Max with 64Gb RAM, running OS Tahoe Ver 26.1.   I have two DELL U2723QE 27 inch displays (one primary, one secondary) with 3840x2160 resolution. 

I have run out of ideas as to how to fix this, so would be very glad of any advice community members can offer please.