Videos cause Lightroom Classic 12.0 to freeze

Adobe chat people have advised me that my computer (2017 iMac running MacOS 12.6) may not be powerful enough to process .mov or .mp4 files larger than, say, 20 MB with Lightroom Classic 12.0. Working with video files stalls or freezes LR. Sometimes after a freeze of 30 minutes, the only way I can resume work in LR is to do a Force Quit, thus losing any previous work.

Can I extend the life of my computer if I revert to an earlier version of LRC?

Thanks for any advice!