Sorry Bret now sent to the list
2 windows open that dont use the same profile: so when running in
private mode I am not running as the same user logged on to the other
instance(window).
so I am not logged into youtube when surfing in private mode but in normal mode (eg the other window) I am signed into youtube.
I am pretty sure this was possible in the past and that is what happens in chromium
So my system has almost 0 cpu usage when browsing and my old computer i3 4 cpu 32GB or even 16GB ram worked fine (really snappy) probably with an older version of debian stable. My current system only uses an up to date debian stable and firefox from debian stable (probably security updates). Now its possible something to do with ublockorigin but the two sites that show a slowdown are youtube and another piece of software called dxtrade (I think i disabled ublock on dxtrade). Everything seems to start off fine but the longer the windows are open or more windows are open the youtube tabs or dxtrade just seem to freeze. I am pretty sure its not a internet speed issue because i am not using high res video or running 4 videos at once. And of course I switch to chromium and everything is perfect.
Anyway very strange
Thanks Dan