Performances serious problem cubase 12.0.52 (and previous v12 ...)

I totally uninstalled my protection software (anti-virus) and restart the PC, Here is a little video in real time of the start and opening of a project (not big project so a raisonnable number of tracks but nothing extraordinary …) I don’t know what kind of pb there is but there is … my machine is powerfull (see description in video) - maybe windows 11 is the issue … ? :