Audio Part Editor zooming=sluggishness


I’m trying to edit two long audio events in the audio part editor and as soon as I start to zooming in to get a more precise edit the events start to move slow to the point that Cubase seems to freeze…impossible to move the events for precise edit.Zooming out seems to restore the ability to move audio parts in a normal way.
This makes audio part editor unusable for me.
I experimented with short audio parts and the sluggishness is present but more or less allows to work.
Never happened this to me before…any ideas?
Win 10 64 (latest update) Cubase 9.5.10.

In 9.0.3 all working fine…should be related to the new video engine

This issue remains in 9.5.20…