Prem Elements 2020 after some time editing freeze-crash-requires Win11 re-boot to restart PE

Content from DVD (PAL) through Handbrake and then first pass through PE2020 to clip content and crop tape noise using PAL DV Standard profile throughout.

Editing is all cuts only using advanced mode and the preview window to mark in/out. After 15mins actively editing a new project playback becomes fast and choppy and quickly the app freezes. After forced close of PE2020 it hangs when restarting unless I restart Windows first.

I have previously edited other (HD) content using this app & laptop w/o seeing this problem.

I can edit this DVD content on my old Win10 laptop using Premiere Elements 12 without any problems.

My Laptop is Win11 fully up to date, Dell XPS 9510 i7, 16GB RAM, SSD has 800G free.

I have disabled Adobe autogenerate to keep a better margin of RAM free

I have checked the media files I am editing which all play normally in WMP and using MediaInfo they look normal 720x576 (1.85:1) MPEG 4 files. Handbrake produced 704x573 (4:3) files but these seem to have gone through PE2020 when I was making clips without trouble 

I have also removed and re-installed PE2020. (V18 20201207.daily.2234367)

I appreciate that PE2020 is now out of date but if PE12 still works on a low spec Win10 machine I hope there is an answer other than going back to using the old laptop. Any advice and experiences will be much appreciated.